中文   |   English   |   Email Alert
Fig/Tab
Advanced Search
image

Non-Radiative Recombination Losses and Regulation Strategies of Perovskite Solar Cells

Senlin Tang , Huan Gao , Ying Peng , Mingguang Li , Runfeng Chen , Wei Huang

Progress in Chemistry ›› 2022, Vol. 34 ›› Issue (8) : 1706 -1722.

PDF
Progress in Chemistry ›› 2022, Vol. 34 ›› Issue (8) : 1706-1722 DOI: 10.7536/PC210827
research-article
Scan to read & Share
Non-Radiative Recombination Losses and Regulation Strategies of Perovskite Solar Cells
Author information +
History +
PDF

Abstract

Over the past decades, metal-halide perovskite solar cells (PSCs) have seen rapid development and gained extensive attention because of their excellent advantages of high light absorption coefficient, longer carrier diffusion distance, lower preparation cost, etc. By now, the champion power conversion efficiency (PCE) has reached 25.5% within a few decades. However, the PCE of the device is still lower than the Shockley-Queisser (S-Q) theoretical limit due to the fact that various non-radiative recombination losses usually take place during carrier transport process. In this review, we first introduce the device structure and working principle of PSCs, and then summarize common non-radiative recombination loss pathways, including defect-assisted Shockley-Read-Hall (SRH) recombination, interface-induced recombination, Auger recombination, band-tail recombination processes, etc. These recombination modes are the main reasons leading to low efficiency and poor stability of PSCs, and thus have drawn considerable attention among researchers. Based on the latest research works, we summarize the general regulation strategies to reduce the undesired non-radiative recombination processes for the construction of high-efficiency and stable PSCs. These efficient regulation strategies mainly include reduction of perovskite crystal defects, passivation of grain boundary defects, passivation of interface defects and optimization of energy level structure. Finally, the opportunities and challenges for the development prospects of non-radiative recombination regulation are discussed.

Contents

1 Introduction

2 Non-radiative recombination mechanisms

2.1 Carrier generation and recombination

2.2 Defect-assisted recombination

2.3 Interface-induced recombination

2.4 Other non-radiative recombination

3 Regulation strategies to reduce non-radiative recombination

3.1 Reduction of perovskite crystal defects

3.2 Passivation of grain boundary defects

3.3 Passivation of interface defects

3.4 Optimization of energy level structure

4 Conclusion and outlook

Graphical abstract

Keywords

perovskite solar cell / power conversion efficiency / non-radiative recombination / defect-assisted recombination / interface-induced recombination

Cite this article

Download citation ▾
Senlin Tang, Huan Gao, Ying Peng, Mingguang Li, Runfeng Chen, Wei Huang. Non-Radiative Recombination Losses and Regulation Strategies of Perovskite Solar Cells. Progress in Chemistry, 2022, 34(8): 1706-1722 DOI:10.7536/PC210827

登录浏览全文

4963

注册一个新账户 忘记密码

1 Introduction

Efficient and sustainable energy development is the focus of human attention in the 21st century. Organic-inorganic hybrid metal halide perovskite (PVK) materials are ideal materials for photovoltaic active layers due to their low preparation cost, high extinction coefficient, tunable band gap and long carrier diffusion distance, thus showing strong market competitiveness[1⇓⇓⇓~5]. In recent years, with the continuous development of material science and process technology, perovskite photovoltaic devices (PSCs) based on PVK materials have shown excellent photovoltaic performance, and the photoelectric conversion efficiency (PCE) has increased from the initial 3.8% to 25.5%, which is very close to the highest efficiency of 26.7% of monocrystalline silicon cells[1][6]. Nevertheless, this efficiency is well below the Shockley-Quayser (S-Q) limit efficiency (33%). In the S-Q model, it is assumed that all carrier recombination within PSCs is radiative recombination, that is, the number of photons absorbed by the active layer under open-circuit conditions is equal to the number of photons emitted, and this recombination process is also called "radiative limit"[7]. To obtain a high PCE, it is necessary to ensure as little carrier recombination as possible. In the process of carrier recombination, radiation recombination is unavoidable and has little effect on device performance. In contrast, non-radiative recombination causes energy loss, which in turn reduces the PCE. In the non-radiative recombination process, the energy generated by electron-hole pair recombination will be transferred to the surrounding lattice in the form of heat, resulting in low open-circuit voltage (VOC), fill factor (FF), short-circuit current density (JSC) of PSCs.
At present, PSCs are mainly divided into three kinds of device structures: mesoporous structure, normal planar structure and inverted planar structure. The basic structure of PSCs includes an ITO/FTO anode, a metal cathode, an electron transport layer (ETL), a hole transport layer (HTL), and a PVK active layer. The common PVK active layer is divided into three-dimensional structure and two-dimensional structure. The three-dimensional PVK crystal structure is expressed as ABX3, as shown in Figure 1A, where the A-site is a monovalent cation.Such as CH3NH3+(MA+), HC(NH2)2+(FA+), Cs+;B sites are divalent cations,The Pb2+, Sn2+;X sites are halogen anions, such as I-, Br-, Cl-. The A-site atoms of the crystal structure constitute a cubic unit cell, with the B-site atoms at the body center and the X-site atoms at the face center. Its structural stability is determined by the Goldschmidt tolerance factor ( t) versus the octahedral factor ( v), and the tolerance factor t = ( R A + R X ) / 2 ( R B + R X ) , octahedral factor v = R B / R X , R A 、 R B 、 R X is the ionic radius of A, B, X, respectively. The above two parameters have a certain fluctuation range (0.81 < t > 1.11, 0.44 < v > 0.90), so the crystal possesses good structural stability and high defect tolerance. As mentioned above, the radius of A-site, B-site and X-site atoms determines the tolerance factor of PVK. When the radius of A-site ions is too large, the dimensionality of PVK will be reduced, forming quasi-three-dimensional, quasi-two-dimensional, two-dimensional or two-dimensional/three-dimensional mixed structures[8,9]. PVKs of different dimensions have different materialization properties. Under the same circumstances, the two-dimensional PVK structure has higher stability than the three-dimensional structure, so the environmental stability of the device can be increased by constructing a low-dimensional structure on the surface of the three-dimensional PVK; At the same time, the low-dimensional structure can also passivate the surface defects and inhibit the non-radiative recombination, and ultimately improve the overall performance of the device[10⇓⇓~13].
At present, the certified JSC of PSCs has reached more than 26 mA·cm-2, but the VOC and FF are still far below the theoretical limit (1.33 V and 91%)[14][15]. Therefore, VOC and FF need to be further improved if PCE is to continue to be improved. The VOC of PSCs is closely related to FF and nonradiative recombination. In organic photovoltaic devices (OPVs), the active layer composed of donor/acceptor materials can easily generate charge transfer States (CT States), which in turn cause non-radiative recombination, resulting in lower VOC. Unlike OPVs, in PSCs, the excitons generated in PVK materials are easily separated to form carriers, so the non-radiative recombination process mainly occurs in the carrier transport process[16,17]. Charge carriers will be captured by various defects in the transmission process, resulting in energy loss, which makes the difference between electron and hole quasi-Fermi level splitting (QFLS) decrease, resulting in low VOC of PSCs[15,18]. In PSCs, the main types of non-radiative recombination are defect-assisted recombination, interface-induced recombination, Auger recombination, and band-tail recombination[19]. In order to further improve the PCE and enhance the working stability of PSCs, it is very important to minimize the non-radiative recombination loss.
In this paper, the basic principles of non-radiative recombination in PSCs are summarized, and the adverse effects of two main non-radiative recombination modes, defect-assisted recombination and interface-induced recombination, on the device performance are discussed. In order to make PSCs closer to the radiation limit and improve the performance of devices, researchers have developed several effective measures to suppress non-radiative recombination. In this paper, the control measures to inhibit non-radiative recombination are summarized from four aspects: reducing PVK crystal defects, passivating grain boundary defects, passivating interface defects and optimizing energy level structure. Finally, the development and application prospects of PSCs are prospected.

2 Non-radiative recombination pathway and mechanism

When PSCs work, the non-radiative recombination process of carriers will greatly reduce the photoelectric performance. It is undoubtedly of great significance to narrow the gap between PSCs and the ultimate efficiency of S-Q theory by deeply studying the non-radiative recombination mode and mechanism and revealing the root cause of energy loss.

2.1 Carrier generation and recombination

To achieve the ideal efficiency of PSCs, the active layer needs to have a high extinction coefficient, and the generated carriers can be smoothly transported to the two electrodes. As a direct band gap semiconductor, PVK has a high absorption coefficient of 10-5cm-1. Therefore, PVK films with a thickness of only 300 ~ 500 nm can absorb most of the incident light in the solar spectrum[20]. Although it has been reported recently that there is a sub-band gap about 60 meV below the conduction band of PVK, subsequent experiments show that the properties of this indirect semiconductor have little effect on its photoelectric conversion process, and the device efficiency can not be greatly improved based on this[21,22]. As shown in fig. 1b, when a photon with an energy above the band gap is incident on the PVK active layer, an electron in the valence band (VB) is excited to a high level in the conduction band (CB)[23]. These hot carriers release energy and gradually cool (10 ∼ 85 fs) to the bottom of the CB[24]. In this process, the electron at the active layer CB and the hole at VB will be extracted by the corresponding transport layer or recombined radiatively or non-radiatively.
The S-Q limit describes the thermodynamic theoretical limit of single-node PSCs in which only radiative recombination (Figure 2A) occurs[7,25,26]. The theoretical calculation ignores the energy loss caused by non-radiative recombination, while the actual efficiency of PSCs is often lower than the S-Q limit efficiency due to various energy losses in the actual work. The energy loss of PSCs can be divided into two types: (1) photon absorption loss, which is related to the transmittance of the electrode and transport layer and the absorbance of the active layer[19]. The transmittance of the electrode and transport layer is not high, and the light absorption rate of the active layer is too low, which will lead to low carrier yield and poor PCE of the device. (2) The loss in the process of carrier transportation, which includes the loss caused by the series and parallel resistance in the device and the non-radiative recombination loss caused by the poor quality of the film, that is, the carrier is captured by the internal deep defect state energy level in the process of transportation or the carrier can not be effectively extracted due to the mismatch of the interface energy level arrangement. The loss path of category (1) is related to the material of each functional layer, and the loss degree is often reduced through certain process design. Type (2) loss is the main energy loss source of PSCs and needs to be focused on. There are two main non-radiative recombination modes affecting type (2) loss: defect-assisted recombination (Fig. 2b) and interface-induced recombination (Fig. 2C). The defect-assisted recombination depends on the energy level depth and density of defect States, while the interface-induced recombination is related to the surface defects and the energy level matching of each functional layer.

2.2 Defect-assisted recombination

Defect-assisted recombination is also known as Shockley-Reed-Quayser (SRH) recombination, as shown in Figure 2b. The main process of recombination can be expressed by the following equation:[26,27]
d n d t = - k 1 n - k 2 n 2 - k 3 n 3
Where n is the photogenerated carrier density and k 1 、 k 2 、 k 3 is the recombination rate constant for defect-assisted (monomolecular), radiative (bimolecular), Auger recombination. At low density of excited States, carriers tend to recombine in the form of unimolecular recombination, such as holes and electrons interacting with oppositely charged defects, respectively. As the density of excited States increases, most of the unimolecular decay channels tend to be saturated, and the excess free carriers begin to adopt the bimolecular recombination mode. At even higher excitation densities, Auger recombination dominates. Among the three recombination pathways, defect-dominated unimolecular recombination is the main cause of non-radiative recombination loss, while Auger recombination is secondary[26].
Taking the common lead methyl amine iodide (MAPbI3)PVK system as an example, the defect types of MAPbI3 mainly include point defects and high-dimensional defects[27⇓~29]. As shown in fig. 3,Point defects include vacancies (VMA, VPb, and VI), interstitials (MAi,Pbi and Ii) and antisite (MAPb, MAI,PbMA 、PbI 、UIMA UNIPb High-dimensional defects mainly refer to dislocation, grain boundary, deposition and so on. Researchers often study the subband gap state and formation energy of point defects by density functional theory (DFT). The results show that,VMA 、VPb 、VI 、MAPb 、MAI, MAi and Ii are shallow defect States,Has a lower formation energy. However, point defects with deep defect state energy levels (such as IMA, IPb, PbMA, PbI and Pbi) need higher formation energy during the fabrication of PSCs[30,31]. The shallow defect States existing at the grain boundary and surface of PVK can cause the voltage loss of PSCs. At the same time, due to the diversity of the composition and fabrication process of PSCs, some high formation energy defects (PbMA, PbI) also appear and affect the device optoelectronic performance[32,33]. The key to future research is to determine the extent to which various types of point defects affect non-radiative recombination.

2.3 Interface-induced recombination

The occurrence of interface-induced recombination is related to two factors: firstly, the density of defect States on the surface of PVK active layer is too high, and the carriers are trapped in the process of movement; Secondly, the energy level structure of the active layer is not matched with that of the transport layer, which produces an interface barrier to enrich or recombine carriers at the interface[34⇓⇓~37]. As shown in fig. 2C, the interface-induced recombination includes recombination caused by internal defects of the PVK active layer (Type I), recombination caused by energy level mismatch and internal defects of the PVK layer (Type II), recombination caused by reverse movement of electrons (holes) due to energy level mismatch (Type III), and recombination due to internal defects in the transport layer (Type IV)[26].
An ideal charge transport layer needs to maintain a good energy level alignment with the active layer and has a low density of defect States. Only by taking into account the two factors, can the carrier be effectively extracted, and then ensure that the QFLS is not reduced due to the recombination of carriers[26].

2.4 Other non-radiative recombination

In addition to defect-assisted recombination and interface-induced recombination, Auger recombination, band-tail recombination, electron-phonon coupling, etc. Exist in PSCs. As shown in Figure 4A, Auger recombination has two channels: direct recombination and indirect recombination, which belong to intrinsic recombination like radiative recombination, and the degree of recombination is related to the concentration of carriers[38]. Under standard illumination AM 1.5 G, the concentration of PSCs carriers is about 1013~1015cm-3, and Auger recombination can be neglected under this condition[39]. It was found that due to the activity
The difference between the layer composition and the preparation method will produce a sub-band gap energy level in the active layer. These levels act as recombination centers that reduce the lifetime of carriers, and this recombination is called band-tail recombination[40]. Specifically, defects, compositional inhomogeneity, and doping in PVK can cause structural disorder, which leads to a decrease in the local potential near CB and VB, resulting in band tail traps near the energy band (as shown in Figure 4B). For example, the change in electrostatic potential caused by the difference in the orientation of FA cation dipoles is manifested as an Urbach band tail in the absorption spectrum. Charge recombination of carriers at the band tail results in a decrease of the radiated energy by tens of megaeV, resulting in a decrease of the VOC[41⇓~43]. At present, there are two main mechanisms to explain the band-tail recombination: (1) hopping model, that is, electrons transition between different energy levels, which can be captured by defects in the process; (2) Multiple trapping model, in which high-energy electrons relax to release energy to lower energy levels. This model assumes that carriers can escape traps only through thermal activation and then be trapped again[44]. In 3D PSCs, the cubic crystal structure of PVK has a certain defect tolerance. In 2D PSCs, the scattering of polar optical phonons and charged defects can be screened by the Coulomb potential energy. However, the transport of charge carriers is inevitably affected by electron-phonon coupling, which will reduce the diffusion length and radiation efficiency of charge carriers. Generally, the photoluminescence intensity is enhanced and the carrier mobility is improved by reducing the electron-phonon coupling through medium confinement[45,46]. Although Auger recombination, band-tail recombination and electron-phonon coupling have important effects on carrier mobility, they are not the main factors affecting the energy loss of PSCs. Therefore, this paper mainly discusses defect-assisted recombination and interface-induced recombination and the related regulatory measures.

3 Measures and strategies to reduce non-radiative recombination

3.1 Reducing perovskite crystal defects

When PSCs work, carriers are generated and diffused in the PVK layer and extracted by the transport layers on both sides. Therefore, the quality of PVK directly affects the photoelectric properties of PSCs. It is well known that PVK thin films with uniform thickness, high crystallinity and large grains contain low density of bulk defect States, which is helpful to the transport of carriers, reduce ion migration and halide segregation, and then inhibit non-radiative recombination, improve the PCE and working stability of devices[47,48]. At present, solvent engineering, additive engineering, thermal annealing process and other methods are often used to control grain growth to achieve the purpose of reducing crystal defects. Single crystal PVK thin film has been favored by researchers in recent years because of its perfect structure with zero defects.
(1) solvent engineering
Solvent engineering plays an important role in adjusting the crystallization kinetics of PVK. Using the appropriate precursor solvent can improve the film quality of PVK and reduce the crystal defects. Initially, the mixed solvent of α-butyrolactone (GBL) and dimethyl sulfoxide (DMSO) was used to improve the quality of PVK films by forming an intermediate phase (MAI-PbI2-DMSO) with methyl ammonium iodide (MAI) and lead iodide (PbI2). Similarly, the mixed solution constructed by dimethylformamide (DMF) and DMSO can form an intermediate phase with PVK components, thereby adjusting the crystallization rate of PVK and finally preparing smooth and uniform PVK films with few defects and high crystallinity[49]. More importantly, the flat and dense film structure can isolate ETL and HTL, prevent the recombination of carriers caused by their direct contact, and have a positive impact on the improvement of PCE of the device[50,51]. In addition, it was found that the precursor solutions composed of N-methylpyrrolidone (NMP), acetonitrile, ether and DMF could also affect the crystallization process of PVK[52][53][54]. As shown in figs. 5a-c, the PVK film prepared by introducing NMP as the precursor solvent, which has stronger electron-donating ability than DMSO, is more compact and flat[52]. Recently, the ionic liquid methylamine formate (MAFa) was found to improve the crystallinity and stability of PVK as a precursor solvent. During the preparation of methylamidinium lead iodide (FAPbI3) film by two-step method, the formate group in MAFa can chelate with lead, and the amino group can form hydrogen bond with free iodide ion. This process pulls lead iodide crystals into regular arrangement and forms nanoscale "ion channels". These ion channels can accelerate the entry of organic cations into the interior of the PbI2 film and react with PbI2 to form a stable black phase FAPbI3 film. Meanwhile, the formate ions remaining at the grain boundary can passivate the defects in situ[55]. ILs have also been well used in all-inorganic PSCs. Using methylamine acetate (MAAc) as solvent, a pinhole-free, uniform and compact CsPbI3-xBrx film with a PCE of 17.10% can be obtained without using an anti-solvent[56]. The emergence of these new processes has further promoted the development of solvent engineering.
(2) Additive engineering
Additive engineering is a technology that can improve the crystal quality and photoelectric performance of PVK. It has been reported that many additives can produce PVK grains with low defects, high crystallinity and large size[57]. The introduction of inorganic alkali halides can adjust the distribution of halogenated anions on the substrate, reduce the formation of defects and improve the crystallinity, such as CsI and RbI, which have been applied to the composition adjustment of PVK[58,59]. The interaction mechanism between metal ions and PVK has also been systematically studied. For example, the Rb+ can improve the crystallinity as well as the VOC, and for the PVK system with a band gap of 1. 63 eV, the VOC can reach 1. 24 V[59]. The introduction of suitable metal atoms not only contributes to the improvement of device efficiency, but also has a positive impact on the stability of the device[60]. For example, Cs2+ doping in the FAPbI3 can stabilize the lattice and significantly improve the operational stability of the device[61]. In addition, organic molecular additives can also optimize the quality of PVK films and reduce crystal defects. For example, by adding methyl ammonium chloride (MACl) in the FAPbI3, the grain size of PSCs can be increased by 6 times, the crystallinity can be increased by 33 times, and the PCE of the final device can reach 23. 48%[62]. In the early research work, it was found that the photochemically active additive benzoquinone (BQ) added in MAPbI3 could coordinate with MAI to slow down the crystallization rate of PVK and obtain large-sized and highly crystalline grains[63]. N, 1-diiodoformamidine (DIFA) can be used as an additive in the FA0.85MA0.15PbI3 precursor solution to prepare high-quality films with micron-sized grains, which greatly reduces the density of defect States and prolongs the carrier lifetime. The PCE of the device based on the DIFA additive is improved from the initial 19.07% to 21.22%[64]. As shown in Fig. 6, ammonium benzenesulfonate (ABS), as a bifunctional additive, can reduce the crystallization rate and improve the crystallinity and carrier diffusion length by forming an intermediate phase with PVK. At the same time, the characteristics of its amphoteric molecules can also repair the surface ionic defects[65].
(3) Thermal annealing process
The annealing process of the active layer will affect the growth of PVK, and various defects of the crystal are also produced in this stage. For example, organic cation and halide anion vacancies are produced at high temperatures, and atomic inversion is caused by atomic disorder deposition. Therefore, researchers have developed a variety of annealing processes to improve the quality of PVK films. The PVK after the low temperature pre-annealing is turned over, so that the PVK layer is contacted with the hot stage for high temperature annealing. This strategy can reduce the evaporation rate of the solvent (DMSO), and the strong interaction between DMSO and PVK can effectively reduce the surface energy of the (110) crystal face, resulting in millimeter-scale MAPbI3 grains and reducing the defects in the crystal[66]. It has also been reported that a PbI2 capping layer is introduced before annealing of PVK, which is dissolved by DMF and DMSO volatilized during annealing, and then diffuses into the MAPbI3 film. This strategy can increase the surface energy of PVK particles, and the small particles undergo Oswald ripening, resulting in the increase of grain size and the formation of (110) crystal orientation, which is conducive to carrier transport[67]. It has also been found that pre-deposition of phenyl -C61- methyl butyrate (PCBM) on PVK precursor films can also inhibit the volatilization of solvent during annealing, reduce the density of nucleation sites, and obtain films with large grains[68,69]. In the two-step method, NMP was added to the MAI solution in isopropanol (IPA), and a quartz flake was used to cover the active layer for annealing, allowing the solvent to interact with PVK for a longer time. Because the electron donating ability of NMP is larger than that of DMF, the combination of NMP and PVK is stronger, the morphology of PVK can be controlled and the grain size can be increased by the annealing process[70]. In addition, the surface of PVK film annealed in advance was treated with IPA vapor, which could dissolve the rough protuberances on the surface and some residual fine grains.
By covering the quartz plate and applying a certain pressure for re-annealing, the effect of grain boundary fusion can be achieved due to the ion diffusion caused by pressure and temperature. The process helps to eliminate defects, increase grain size, and form smooth films[71,72]. A similar process, shown in Figure 7 a and B, uses methylamine gas to react with PVK to produce a liquid mesophase, which expands in volume and interconnects with the surrounding liquid phase as it absorbs methylamine gas, increasing the coverage of PVK. With the volatilization of methylamine gas, PVK nucleates and grows again. The process can increase the grain size and avoid the problems of pinholes and poor film coverage[73,74].
(4) preparation of single crystal
Although researchers have made great progress in solvent engineering, additive engineering and thermal annealing process, the polycrystalline PVK thin films still have many defects, which are not conducive to carrier transport and long-term stability of the device. Compared with polycrystalline PVK, single crystal PVK has a lower density of defect States and a carrier diffusion length of up to 175 μm, which has attracted the attention of researchers in recent years[75]. Most of the single crystal PVK prepared in solution is bulk, which is difficult to prepare vertical structure PSCs, so this kind of single crystal is often used to prepare lateral structure PSCs and other optoelectronic devices[76⇓~78]. Some researchers have also carried out systematic studies on the photoelectric properties of bulk PVK single crystals[75,79]. At present, the spatial confinement method is commonly used to prepare vertical PSCs, in which two glass sheets are used to form an adjustable confined space between the precursors, and the capillary is used to realize the dynamic flow of the precursor solution, and the micron-sized single crystal PVK is obtained by inverse temperature crystallization[80]. In the actual single crystal preparation process, a confined space is formed by means of two ITO glass substrates spin-coated with HTL, as shown in Fig. 8 a ~ C. The commonly used HTL is poly [bis (4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA), which has strong hydrophobic properties and can increase the diffusion distance during the deposition of MAPbI3 atoms, which is helpful to grow a continuous PVK single crystal film directly on the HTL and facilitate the later ETL deposition[81]. Since then, the space confinement method has been widely used. In order to further improve the crystallization quality, the researchers also used the gradient heating method to induce the continuous growth of grains, and the PCE reached 21.09%[82]. In order to further reduce the film preparation temperature, the researchers added propylene carbonate to the precursor solution to accelerate the nucleation of PVK, and successfully prepared PVK films with good crystal orientation, high crystallinity and few crystal defects at low temperature, which effectively reduced the non-radiative recombination loss on the surface of PVK, and finally increased the VOC from 1. 08 eV to 1. 15 eV, with a PCE of 21. 9%[83]. In order to make PVK easier to nucleate in solution, some researchers have introduced microcrystalline seeds into the confined space as nucleation sites to induce the formation of single crystal films[77,84].

3.2 Passivated grain boundary defect

As a semiconductor device, the electrical properties of PSCs can be greatly reduced by the defects located at the grain boundaries of the PVK layer[85]. At the beginning of the development of PSCs, the influence of grain boundaries on the performance of PSCs has been neglected, and until recent years, people have begun to pay attention to the passivation strategy for grain boundaries. Researchers used Kelvin force microscopy and conductive atomic force microscopy to characterize PVK films, and found that carriers need to cross the barrier at the grain boundary in the process of transmission, so the existence of grain boundary is not conducive to the long-distance transmission of carriers[86]. The experimental results also show that the existence of grain boundaries can lead to the generation of non-radiative recombination, which ultimately reduces the electrical properties of the PVK active layer[87]. Therefore, passivating grain boundary defects is also one of the important ways to inhibit the non-radiative recombination of PSCs.
(1) Additive engineering
Increasing the content of PbI2 is an effective way to passivate the grain boundary defects of PVK, and the excessive PbI2 will adhere to the grain boundary to repair the defects during the crystallization of PVK[88,89]. As shown in Fig. 9 a, B, the band gap of PbI2 (2.3 eV) is wider than that of PVK (1.5 eV), and its CB and VB are located above and below PVK, respectively, which can form an energy barrier to prevent non-radiative recombination at grain boundaries. In addition, PbI2 is able to change the bending direction of the grain boundary band, thereby reducing the recombination of carriers at the interface[90]. However, PbI2 will also reduce the stability of the device while passivating the grain boundary, and the precise control of the content is also a major challenge[91,92]. As shown in Fig. 9c, the HPbI3 additive combines the advantages of HI and PbI2, which can not only passivate the grain boundary defects, but also regulate the PVK crystallization process to obtain large-sized grains, and ultimately improve the PCE and stability of PSCs[93]. It has been reported that the addition of excessive MAI can also passivate the grain boundary and improve the energy level matching[94][95].
However, protocols using excess PbI2 or MAI have stringent stoichiometric and manufacturing environmental requirements. Therefore, people are also developing new additive control schemes, such as adding metal cations in the precursor, which can also effectively reduce grain boundary defects and improve the PCE and stability of devices. There are three kinds of metal ion additives reported so far: firstly, monovalent metal cations such as Cu+, Ag+ and Li+ are used to reduce the density of defect States and improve the electrical properties of PSCs[97,98]; Secondly, divalent metal cations such as Mn2+, Co2+ and Zn2+ were used to adjust the VB of PVK to optimize the morphology and improve the stability[99⇓⇓⇓~103]. Again, PSCs were modified by trivalent metal cations such as Ln3+, Al3+, Rh3+, and Eu3+[96,104⇓~106]. Specifically, Eu3+ doped PVK has good light stability and still maintains 92% PCE after continuous illumination for 1500 H[5]. As shown in Fig. 9 d, when Rh3+ is doped in the PVK precursor solution, the ordered deposition of atoms is induced by the interaction between chemical bonds and [PbI6]4-, which slows down the crystallization rate of PVK, and then promotes the formation of a PVK film with large grain size and uniformity, and also plays a role in passivating grain boundary defects[96].
(2) Post-treatment process
Through the post-treatment process, some organic compounds with electron transfer properties can react with PVK by Lewis acid and base, which can also achieve the purpose of grain boundary passivation. Lewis acid can accept electrons from negatively charged defects, and Lewis base can provide electrons to positively charged defects, which can be coordinated to passivate defects[107]. Various fullerenes and their derivatives, such as C60 and its self-assembled monolayer (C60-SAM), PCBM and its isomer α-bis-PCBM, are representative Lewis acids in PSCs[108⇓~110]. For example, α-bis-PCBM dispersed in the antisolvent chlorobenzene can control the growth of PVK crystals, and can also passivate halogen-induced deep level traps, so that the modified PSCs have good photoresponse and stable power output[110]. Lewis bases corresponding to Lewis acids mainly include oxygen donors, sulfur donors, nitrogen donors, etc., which mainly play the role of electron donors[111,112][113][114]. For example, the conjugated carboxyl group (R — C = O) of 1,3,7-trimethylxanthine (caffeine) can interact with the Pb-I bond to form a strong Lewis acid-base adduct, and the prepared PVK film grains have the characteristics of preferred orientation, thereby finally improving the VOC[111]. It has also been reported that polybithiophene imide (PBTI) was spin-coated on the surface of PVK layer, and the polymer can be embedded into the grain boundary to control the grain growth, as shown in fig. 10a and B. The PBTI backbone contains a large number of S atoms, which can reduce the grain boundary defects and improve the carrier lifetime by forming Pb-S coordination[113]. In addition, a variety of functional groups in the molecule can be used to repair different types of defects in PVK at the same time. For example, the carboxyl group (— COOH) and amino group (—NH2) of d-4-tert-butylphenylalanine can repair charged defects through electrostatic interaction, while the iodine defect in PVK can be repaired by aromatic structure, and the tert-butyl group of the benzene ring will enhance the electron-donating ability of the benzene ring, thus better passivating Lewis acid-type surface defects. Finally, the carrier lifetime increases to a loss of only 0.34 V in the 930.30 ns,VOC[114]. Similarly, the pyridine and carboxylic acid groups contained in the molecule can interact with the Pb-I bond to achieve the effect of multiple passivation by post-treatment with pyridine dicarboxylic acid (PDA), which can effectively repair the surface and grain boundary defects of PVK[115]. As shown in Fig. 10c – e, 4-dimethylaminopyridine (DMAP) can selectively passivate the uncoordinated Pb2+ at the grain boundary, reduce the recombination of carriers at the grain boundary, and improve the contact quality of HTL/PVK, and the device PCE increases from 20.04% to 22.4%[116]. As shown in Figure 10 f, G, 2-aminoterephthalic acid contains one benzene ring, one amino group (—NH2), and two carboxyl groups (— COOH). Because of the firm structure of benzene ring, strong π-π bond interaction and high cohesive energy of molecules, molecules are easy to aggregate on the grain boundary, carboxyl groups can interact with Pb2+ or I-, while amino groups can fill MA vacancies and promote the preferred orientation growth of MAPbI3. At the same time, the PVK film treated by crosslinking passivator has a larger contact angle, which can more effectively resist the erosion of water, which is also the reason for the improvement of the stability of the modified device[117].

3.3 Passivation interface defect

In the previous section, by adding passivation molecules into the precursor solution or spin-coating on the surface of PVK active layer, the effective passivation of grain boundary defects can be achieved and the non-radiative recombination can be reduced. In fact, in addition to the bulk and grain boundaries of PVK materials, the contact interface between the PVK active layer and the transport layer is also an important place where non-radiative recombination occurs. Interface defects can capture the carriers in transit, which seriously affects the carrier transport efficiency. In order to solve the above problems, interface engineering is often used to passivate the surface defects of PVK and improve the transport efficiency of carriers. In order to better extract the carriers from the transport layer, the PVK layer is often spin-coated with passivation molecules by post-treatment to modify the surface, or a buffer layer is introduced between the PVK layer and the transport layer to improve the transport efficiency of the carriers. A large number of studies have shown that the post-treatment of PVK with the help of passivation solution can effectively improve the photoelectric properties of PVK layer. As shown in Fig. 11A and B, when 1-hexylpyridinium chloride (EPC) is used for post-treatment, N in pyridine has high electronegativity, which can transfer part of the charge from Pb to pyridine to produce coordination, while ethyl and pyridine can increase the hydrophobicity of the interface, and Cl also helps to passivate defects, thereby improving the crystallinity of PVK[118]. For another example, tetra-n-octylammonium bromide (TOAB) can be used to passivate grain boundaries and surface defects, enhance the light absorption ability of PVK and form a dipole moment on the surface, and ultimately improve the carrier extraction efficiency[119]. A small amount of tetrabutylammonium iodide (TBAI) was spin-coated on the surface of the unannealed PVK layer, which avoided the enrichment of excessive I- on the surface of PVK and formed coordination with Pb2+. The density of defect States was reduced from the original 1.62×1016cm-3 to 1.24×1016cm-3, and the final PCE reached 21. 28%[120].
The introduction of a buffer layer at the PVK layer/transport layer interface is also an effective way to modify the interface of PSCs. For example, the insertion of an ultrathin poled ferroelectric polymer layer can reduce the surface defects and improve the energy level alignment, and minimize the energy loss caused by interface-induced recombination[121]. Poly (methyl methacrylate) (PMMA) was introduced into the /TiO2 interface of PVK layer to form an ultrathin polymer passivation layer. As a Lewis base, the carboxyl group of PMMA can strongly interact with the uncoordinated Pb2+, which can effectively reduce the interface defects and increase the VOC from 1. 10 V to 1. 18 V[122]. Through further application, as shown in Fig. 11c-e, after the top and bottom surfaces of the PVK active layer are passivated by PMMA at the same time, PMMA can be in good contact with PVK, which will adversely affect the transmission of carriers, but the grain boundary defects are further passivated, the interface non-radiative recombination is suppressed, and the VOC is further improved[123]. Similarly, surface defects can also be passivated by adding a layer of wide-bandgap material on the active layer with narrow bandgap, controlling the selective transport of carriers, and ultimately inhibiting the interfacial recombination of the active layer/transport layer[124]. It is found that large organic cations can be embedded into the three-dimensional PVK lattice to form a low-dimensional PVK. Although its insulating property limits the charge transport in the low-dimensional PVK, its wide band gap can increase the VOC of the device. At the same time, high hydrophobicity can effectively block the erosion of moisture and improve the environmental stability of the device[125]. As shown in Figure 11F, a mixed solution of phenylhexyl ammonium iodide (PEAI) and MAI was used for post-treatment, and PEA+ could replace MA+ to finally self-assemble on PVK to form a dense quasi-two-dimensional layered PVK (PEAMAPI), which has a high CB, can reduce the reverse recombination of electrons, and also plays a role in isolating oxygen and moisture erosion[126]. In addition, as shown in fig. 11g, a thin two-dimensional PVK(PEA2PbI4) can be generated on the top of the three-dimensional PVK layer by using PEAI alone for film post-treatment, thereby effectively improving the efficiency and stability of the device[127]. Due to the coverage of PEAI, the iodine vacancies on the surface and grain boundaries of the PVK layer are effectively filled, and the reduction of point defects significantly improves the carrier transport ability and the working stability of the device[128]. In addition to the passivation effect of interface defects, 2D PVK with a wider band gap can also form a gradient heterojunction with 3D PVK to facilitate charge extraction, which explains the improvement of VOC. The Ruddlesden-Popper (RP) type two-dimensional PVK material thus formed contains hydrophobic groups, thus being able to increase the stability of the device to a certain extent. However, the weak interaction between the layers of this kind of two-dimensional PVK material is difficult to ensure that the material itself has sufficient structural stability. To further improve the structural stability of the material, the researchers used hydrazine cation (H3N+-R-NH3+) instead of monoammonium salt to form a Dion-Jacobson (DJ) -type two-dimensional PVK material. Compared with RP-type two-dimensional PVK, DJ-type two-dimensional PVK has no interlayer van der Waals interaction, and its organic cations are connected with inorganic PVK by hydrogen bonds at both ends of the molecule, so it has better structural stability[129,130].
In summary, the introduction of organic passivation molecules and two-dimensional PVK layer can inhibit the interface-induced recombination and ultimately improve the VOC of PSCs. However, the conductivity of these interface materials is often low, which will hinder the charge transfer between PVK and the transport layer. Therefore, the thickness of these interfacial layers must be precisely controlled to avoid PSCs photocurrent loss.

3.4 Optimized energy level structure

In PSCs, the regulation of the energy levels of various functional layers has always been the focus of researchers. Suitable energy level alignment helps to accelerate the transport, extraction and collection of carriers, while inhibiting their accumulation, recombination and reverse transfer at the interface. In order to selectively transport carriers, the interface between the PVK layer and the transport layer needs to maintain a large Schottky barrier. To achieve an ideal VOC, electrons and holes need to maintain a large difference in QFLS[34]. However, due to the migration of carriers and ions between the PVK layer and the transport layer, it is easy to bend the energy band when PSCs work, resulting in a rapid increase in the density of carriers at the interface and an exponential increase in the degree of interface recombination, which ultimately leads to a decrease in VOC[131,132].
The key to reduce the energy loss is to select the appropriate transport layer materials and construct a good energy level alignment. PTAA and poly [bis (4-phenyl) (4-butylphenyl) amine] (poly-TPD) are often used as HTL in inverted PSCs, and their lower HOMO energy level reduces the interface barrier, which is more conducive to the transport of holes[131]. Traditional ETL, such as C60 and PCBM, often have some problems, such as unstable structure, random molecular orientation, difficult purity control and large barrier between PVK layer, which cause serious energy loss in the use process. The results show that the structural order and carrier mobility can be improved by solvent annealing[133]. In addition, by doping an appropriate amount of C60 into PCBM, the Fermi level (Ef) and conductivity can be improved, and the effective transmission of electrons can be promoted[134]. In addition, the energy level structure can also be improved by introducing an intermediate layer, such as inserting lithium fluoride (LiF) and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) to reduce the energy barrier of PCBM/metal electrode, improve the carrier extraction efficiency and reduce the recombination loss[135]. In addition, it has also been reported that wide band gap polystyrene (PS) is inserted between the PVK layer and the ETL to improve the VOC by reducing the recombination of carriers at the interface (fig. 12 (a))[36].
In the positive PSCs, the small molecule 2,2 ', 7,7' -tetra- (dimethoxydiphenylamine) -spirofluorene (spiro-OMeTAD) has the characteristics of good energy level matching and high hole transport ability, and is often used as HTL. In practical applications, doping or molecular modification is often used to improve the energy level structure of spiro-OMeTAD and promote the transport of carriers[136]. Using Spiro-OMeTAD (DM) modified by small molecules with fluorine-containing terminal groups as HTL can reduce the HOMO energy level, reduce the quasi-Fermi level bending of holes, and increase the VOC[137]. TiO2 and SnO2 are often used to prepare ETL because of their excellent conductivity and good energy level matching with PVK layer. Researchers usually use doping or deposition of double-layer ETL to further improve the extraction efficiency of electrons[132]. For example, doping Li+, In3+, Nb5+, etc. In the TiO2 reduces the CB, when the CB of the TiO2 is lower than that of the PVK layer,The electrons can be effectively extracted by the ETL, the loss in the carrier transmission process is reduced, and finally the VOC is improved[138⇓~140]. In the double ETL PSCs, the majority of the second modification layer can not only passivate the surface defects of the lower ETL, but also form a gradient heterojunction to reduce the band bending between the ETL and the PVK layer. As shown in fig. 12b,Using UNK 1 mesoporous SnO2, SnO2/ mesoporous TiO2,TiO2/PCBM, TiO2/C60, etc., can greatly reduce energy losses[141][141⇓~143]. Although the PCE of PSCs can be improved by optimizing the energy level alignment of PVK and the two side transport layers, some studies suggest that the degree of energy level matching between the PVK layer and the bottom transport layer does not have a great impact on the VOC, and the energy loss at the interface is mainly related to the PVK active layer and the top transport layer[144,145].

4 Conclusion and prospect

In this review, the main pathways of nonradiative recombination are systematically summarized, and the measures and strategies to inhibit nonradiative recombination are summarized. Defect-assisted recombination and interface-induced recombination are the main reasons for the energy loss of devices. At present, the energy loss is mainly reduced through the following two aspects: (1) reducing the defects of PVK crystal, grain boundary and surface, realizing the controllable growth process of PVK through additives, pretreatment, thermal annealing and other processes, and passivating the defects of PVK grain boundary and surface through film post-treatment; (2) To improve the degree of energy level matching and increase the extraction rate of carriers, the specific strategies can be to improve the energy level alignment by adjusting the composition of the transport layer, introducing low-dimensional PVK structure and adding modification layers.
Although researchers have made great progress in inhibiting non-radiative recombination and reducing energy loss, most of the improvement strategies are only the late repair of PVK defects or the adjustment of energy level structure. These measures not only improve the device performance, but also increase the process flow and preparation cost of photovoltaic devices, which is not conducive to the commercial application of PSCs. Therefore, finding a new stable PVK system and developing a PVK preparation process with controllable crystallization process are worthy of future attention of researchers. For example, by designing new organic amine systems, developing low-dimensional PVK materials with wide band gap and high stability, and constructing high-quality three-dimensional PVK films modified by low-dimensional PVK, the generation of defects can be effectively reduced, the recombination of carriers at the interface can be inhibited, the VOC of devices can be increased, and the efficiency and stability of devices can be improved. Develop stable and controllable PVK thin film formation methods, such as epitaxial growth, space confinement and other processes to prepare high-quality oriented PVK thin films with uniform thickness and fewer defects, so as to improve carrier migration efficiency. The development of new PVK system and new process is not only expected to fundamentally reduce the non-radiative recombination process caused by various defects, but also to reduce the environmental dependence of the preparation process and enhance the working stability of the device, which will undoubtedly be an important research direction in the field of PVK-based PSCs in the future.

References

Publishing order | Descend order by publishing year | Descend order by cited within
[1]

Kojima A, Teshima K, Shirai Y, Miyasaka T. J. Am. Chem. Soc., 2009, 131(17): 6050.
[2]

Kim H S, Lee C R, Im J H, Lee K B, Moehl T, Marchioro A, Moon S J, Humphry-Baker R, Yum J H, Moser J E, Grätzel M, Park N G. Sci. Rep., 2012, 2(1): 591.
[3]

Yoo J J, Seo G, Chua M R, Park T G, Lu Y L, Rotermund F, Kim Y K, Moon C S, Jeon N J, Correa-Baena J P, Bulović V, Shin S S, Bawendi M G, Seo J. Nature, 2021, 590(7847): 587.
[4]

Nishimura T, Toki S, Sugiura H, Nakada K, Yamada A. Prog. Photovolt.: Res. Appl., 2018, 26(4): 291.
[5]

Dai Z H, Yadavalli S K, Chen M, Abbaspourtamijani A, Qi Y, Padture N P. Science, 2021, 372(6542): 618.
[6]

Green M A, Dunlop E D, Hohl-Ebinger J, Yoshita M, Kopidakis N, Hao X J. Prog. Photovolt.: Res. Appl., 2021, 29: 657.
[7]

Shockley W, Queisser H J. J. Appl. Phys., 1961, 32(3): 510.
[8]

Sutanto A, Caprioglio P, Drigo N, Hofstetter Y, Garcia-Benito I, Queloz V, Neher D, Nazeeruddin M, Stolterfoht M, Vaynzof Y, Grancini G. Chem, 2021, 7: 1903.
[9]

Lin D X, Xu X, Zhang T K, Pang N N, Wang J M, Li H Y, Shi T T, Chen K, Zhou Y, Wang X, Xu J B, Liu P Y, Xie W G. Nano Energy, 2021, 84: 105893.
[10]

Fu W F, Liu H B, Shi X L, Zuo L J, Li X S, Jen A K Y. Adv. Funct. Mater., 2019, 29(25): 1900221.
[11]

Fan J D, Ma Y P, Zhang C L, Liu C, Li W Z, Schropp R E I, Mai Y H. Adv. Energy Mater., 2018, 8(16): 1703421.
[12]

Koh T M, Shanmugam V, Guo X T, Lim S S, Filonik O, Herzig E M, Müller-Buschbaum P, Swamy V, Chien S T, Mhaisalkar S G, Mathews N. J. Mater. Chem. A, 2018, 6(5): 2122.
[13]

Kuo M Y, Spitha N, Hautzinger M P, Hsieh P L, Li J, Pan D X, Zhao Y Z, Chen L J, Huang M H, Jin S, Hsu Y J, Wright J C. J. Am. Chem. Soc., 2021, 143(13): 4969.
[14]

Jeong J, Kim M, Seo J, Lu H Z, Ahlawat P, Mishra A, Yang Y G, Hope M A, Eickemeyer F T, Kim M, Yoon Y J, Choi I W, Darwich B P, Choi S J, Jo Y, Lee J H, Walker B, Zakeeruddin S M, Emsley L, Rothlisberger U, Hagfeldt A, Kim D S, Grätzel M, Kim J Y. Nature, 2021, 592(7854): 381.
[15]

Sarritzu V, Sestu N, Marongiu D, Chang X Q, Masi S, Rizzo A, Colella S, Quochi F, Saba M, Mura A, Bongiovanni G. Sci. Rep., 2017, 7(1): 1900221.
[16]

Tang A L, Song W, Xiao B, Guo J, Min J, Ge Z Y, Zhang J Q, Wei Z X, Zhou E J. Chem. Mater., 2019, 31(11): 3941.
[17]

An N, Cai Y H, Wu H B, Tang A L, Zhang K N, Hao X T, Ma Z F, Guo Q, Ryu H S, Woo H Y, Sun Y M, Zhou E J. Adv. Mater., 2020, 32(39): 2002122.
[18]

Wang B, Li H, Dai Q Q, Zhang M, Zou Z G, Brédas J L, Lin Z Q. Angew. Chem. Int. Ed., 2021, 60(32): 17664.
[19]

Chen J Z, Park N G. Adv. Mater., 2019, 31(47): 1803019.
[20]

de Wolf S, Holovsky J, Moon S J, Löper P, Niesen B, Ledinsky M, Haug F J, Yum J H, Ballif C. J. Phys. Chem. Lett., 2014, 5(6): 1035.
[21]

Hutter E M, Gélvez-Rueda M C, Osherov A, Bulović V, Grozema F C, Stranks S D, Savenije T J. Nat. Mater., 2017, 16(1): 115.
[22]

Wang T Y, Daiber B, Frost J M, Mann S A, Garnett E C, Walsh A, Ehrler B. Energy Environ. Sci., 2017, 10(2): 509.
[23]

Gao F, Zhao Y, Zhang X W, You J B. Adv. Energy Mater., 2020, 10(13): 1902650.
[24]

Wei Q, Yin J, Bakr O M, Wang Z, Wang C H, Mohammed O F, Li M J, Xing G C. Angew. Chem. Int. Ed., 2021, 60(19): 10957.
[25]

Tress W, Marinova N, Inganäs O, Nazeeruddin M K, Zakeeruddin S M, Graetzel M. Adv. Energy Mater., 2015, 5(3): 1400812.
[26]

Luo D Y, Su R, Zhang W, Gong Q H, Zhu R. Nat. Rev. Mater., 2020, 5(1): 44.
[27]

Ball J M, Petrozza A. Nat. Energy, 2016, 1(11): 1.
[28]

Jones T, Osherov A, Alsari M, Sponseller M, Duck B, Jung Y, Settens C, Niroui F, Brenes R, Stan C. Energy Environ. Sci., 2019, 12: 596.
[29]

Yang X Y, Ni Y, Zhang Y Z, Wang Y J, Yang W Q, Luo D Y, Tu Y G, Gong Q H, Yu H F, Zhu R. ACS Energy Lett., 2021, 6(7): 2404.
[30]

Moia D, Maier J. ACS Energy Lett., 2021, 6 (4): 1566.
[31]

Yin W J, Shi T T, Yan Y F. Adv. Mater., 2014, 26(27): 4653.
[32]

Wu N, Wu Y, Shen H, Walter D, Duong T, Grant D, Barugkin C, Fu X, Peng J, Mulmudi H. Energy Technol., 2017, 5: 1827.
[33]

Shao Y C, Xiao Z G, Bi C, Yuan Y B, Huang J S. Nat. Commun., 2014, 5(1): 5784.
[34]

Luo D Y, Li X Y, Dumont A, Yu H Y, Lu Z H. Adv. Mater., 2021, 33(30): 2006004.
[35]

Wang Z Y, Zhu X J, Feng J S, Wang C Y, Zhang C, Ren X D, Priya S, Liu S F, Yang D. Adv. Sci., 2021, 8(13): 2002860.
[36]

Wolff C M, Zu F S, Paulke A, Toro L P, Koch N, Neher D. Adv. Mater., 2017, 29(28): 1700159.
[37]

Wolff C M, Caprioglio P, Stolterfoht M, Neher D. Adv. Mater., 2019, 31(52): 1902762.
[38]

Pazos-Outón L M, Xiao T P, Yablonovitch E. J. Phys. Chem. Lett., 2018, 9(7): 1703.
[39]

Dequilettes D, Vorpahl S, Stranks S, Nagaoka H, Ginger D. Science, 2015, 348: 683.
[40]

Leijtens T, Eperon G E, Barker A J, Grancini G, Zhang W, Ball J M, Kandada A R S, Snaith H J, Petrozza A. Energy Environ. Sci., 2016, 9(11): 3472.
[41]

Srimath Kandada A R, Neutzner S, D’Innocenzo V, Tassone F, Gandini M, Akkerman Q A, Prato M, Manna L, Petrozza A, Lanzani G. J. Am. Chem. Soc., 2016, 138(41): 13604.
[42]

Cava R J, Santoro A, Johnson D W, Rhodes W W. Phys. Rev. B, 1987, 35(13): 6716.
[43]

Wright A D, Milot R L, Eperon G E, Snaith H J, Johnston M B, Herz L M. Adv. Funct. Mater., 2017, 27(29): 1700860.
[44]

Rosen M D, Hagelstein P L, Matthews D L, Campbell E M, Hazi A U, Whitten B L, MacGowan B, Turner R E, Lee R W, Charatis G, Busch G E, Shepard C L, Rockett P D, Johnson R R. Phys. Rev. Lett., 1985, 54(8): 853.
[45]

Guo Z, Wu X X, Zhu T, Zhu X Y, Huang L B. ACS Nano, 2016, 10(11): 9992.
[46]

Motta C, Sanvito S. J. Phys. Chem. C, 2018, 122(2): 1361.
[47]

Zhang F, Lu H P, Larson B W, Xiao C X, Dunfield S P, Reid O G, Chen X H, Yang M J, Berry J J, Beard M C, Zhu K. Chem, 2021, 7(3): 774.
[48]

An Q Z, Paulus F, Becker-Koch D, Cho C, Sun Q, Weu A, Bitton S, Tessler N, Vaynzof Y. Matter, 2021, 4(5): 1683.
[49]

Wang M, Cao F R, Deng K M, Li L. Nano Energy, 2019, 63: 103867.
[50]

Zuo C T, Ding L M. Angew. Chem. Int. Ed., 2021, 60(20): 11242.
[51]

Zhao Y P, Zhu P C, Wang M H, Huang S, Zhao Z P, Tan S, Han T H, Lee J W, Huang T Y, Wang R, Xue J J, Meng D, Huang Y, Marian J, Zhu J, Yang Y. Adv. Mater., 2020, 32(17): 1907769.
[52]

Lee J W, Dai Z H, Lee C, Lee H M, Han T H, de Marco N, Lin O, Choi C S, Dunn B, Koh J, di Carlo D, Ko J H, Maynard H D, Yang Y. J. Am. Chem. Soc., 2018, 140(20): 6317.
[53]

Li L, Chen Y, Fan R, Wang X, Zhou H. Adv. Mater., 2016, 28: 9862.
[54]

Xu C Y, Liu Z H, Lee E C. J. Mater. Chem. C, 2020, 8(44): 15860.
[55]

Hui W, Chao L F, Lu H, Xia F, Wei Q, Su Z H, Niu T T, Tao L, Du B, Li D L, Wang Y, Dong H, Zuo S W, Li B X, Shi W, Ran X Q, Li P, Zhang H, Wu Z B, Ran C X, Song L, Xing G C, Gao X Y, Zhang J, Xia Y D, Chen Y H, Huang W. Science, 2021, 371(6536): 1359.
[56]

Wang X J, Ran X Q, Liu X T, Gu H, Zuo S W, Hui W, Lu H, Sun B, Gao X Y, Zhang J, Xia Y D, Chen Y H, Huang W. Angew. Chem. Int. Ed., 2020, 59(32): 13354.
[57]

Haque M A, Troughton J, Baran D. Adv. Energy Mater., 2020, 10(13): 1902762.
[58]

Abdi-Jalebi M, Andaji-Garmaroudi Z, Pearson A, Divitini G, Stranks S. ACS Energy Lett., 2018, 3: 9862.
[59]

Saliba M, Matsui T, Domanski K, Seo J Y, Ummadisingu A, Zakeeruddin S M, Correa-Baena J P, Tress W R, Abate A, Hagfeldt A, Grätzel M. Science, 2016, 354(6309): 206.
[60]

Zhang M M, Zhou W R, Hu W P, Li B R, Qiao Q Q, Yang S F. ACS Appl. Mater. Interfaces, 2020, 12(11): 12696.
[61]

Cao H Q, Dong Z, Qiu Y, Li J Z, Wang Y J, Li Z Y, Yang L Y, Yin S G. ACS Appl. Mater. Interfaces, 2020, 12(37): 41303.
[62]

Kim M, Kim G, Lee T, Choi I, Kim D. Joule, 2019, 3: 2179.
[63]

Qin C J, Matsushima T, Fujihara T, Adachi C. Adv. Mater., 2017, 29(4): 1603808.
[64]

Li H, Wu G, Li W, Zhang Y, Liu S. Adv. Sci., 2019, 6: 1901241.
[65]

Yang Y, Peng H R, Liu C, Arain Z, Ding Y, Ma S, Liu X L, Hayat T, Alsaedi A, Dai S Y. J. Mater. Chem. A, 2019, 7(11): 6450.
[66]

Zhu W, Kang L, Yu T, Lv B, Zou Z. ACS Appl. Mater. Interfaces, 2017, 9: 6104.
[67]

Wang Y, Li J W, Li Q, Zhu W D, Yu T, Chen X Y, Yin L A, Zhou Y, Wang X Y, Zou Z G. Chem. Commun., 2017, 53(36): 5032.
[68]

Cao X B, Zhi L L, Li Y H, Cui X, Ci L J, Ding K X, Wei J Q. RSC Adv., 2017, 7(77): 49144.
[69]

Cao X B, Zhi L L, Li Y H, Fang F, Cui X, Ci L J, Ding K X, Wei J Q. ACS Appl. Energy Mater., 2018, 1(2): 868.
[70]

Zhi L L, Li Y Q, Cao X B, Li Y H, Cui X, Ci L J, Wei J Q. J. Energy Chem., 2019, 30: 78.
[71]

Wang T, Lian G, Huang L P, Zhu F, Cui D L, Wang Q L, Meng Q B, Jiang H H, Zhou G J, Wong C P. Nano Energy, 2019, 64: 103914.
[72]

Fu X W, Dong N, Lian G, Lv S, Zhao T, Wang Q L, Cui D L, Wong C P. Nano Lett., 2018, 18(2): 1213.
[73]

Fan H C, Li F Z, Wang P C, Gu Z K, Huang J H, Jiang K J, Guan B, Yang L M, Zhou X Q, Song Y L. Nat. Commun., 2020, 11(1): 5402.
[74]

Zhou Z M, Wang Z W, Zhou Y Y, Pang S P, Wang D, Xu H X, Liu Z H, Padture N P, Cui G L. Angew. Chem., 2015, 127(33): 9841.
[75]

Dong Q F, Fang Y J, Shao Y C, Mulligan P, Qiu J, Cao L, Huang J S. Science, 2015, 347(6225): 967.
[76]

Liu Y, Dong Q F, Fang Y J, Lin Y Z, Deng Y H, Huang J S. Adv. Funct. Mater., 2019, 29(47): 1807707.
[77]

Gao J, Liang Q B, Li G H, Ji T, Liu Y C, Fan M M, Hao Y Y, Liu S F, Wu Y C, Cui Y X. J. Mater. Chem. C, 2019, 7(27): 8357.
[78]

Gong J D, Yu H Y, Zhou X, Wei H H, Ma M X, Han H, Zhang S, Ni Y, Li Y L, Xu W T. Adv. Funct. Mater., 2020, 30(46): 2005413.
[79]

Gong X W, Huang Z R, Sabatini R, Tan C S, Bappi G, Walters G, Proppe A, Saidaminov M I, Voznyy O, Kelley S O, Sargent E H. Nat. Commun., 2019, 10(1): 1591.
[80]

Liu Y C, Zhang Y X, Yang Z, Yang D, Ren X D, Pang L Q, Liu S F. Adv. Mater., 2016, 28(41): 9203.
[81]

Chen Z L, Dong Q F, Liu Y, Bao C X, Fang Y J, Lin Y, Tang S, Wang Q, Xiao X, Bai Y, Deng Y H, Huang J S. Nat. Commun., 2017, 8(1): 1890.
[82]

Chen Z L, Turedi B, Alsalloum A Y, Yang C, Zheng X P, Gereige I, AlSaggaf A, Mohammed O F, Bakr O M. ACS Energy Lett., 2019, 4(6): 1258.
[83]

Alsalloum A Y, Turedi B, Zheng X P, Mitra S, Zhumekenov A A, Lee K J, Maity P, Gereige I, AlSaggaf A, Roqan I S, Mohammed O F, Bakr O M. ACS Energy Lett., 2020, 5(2): 657.
[84]

Yue H L, Sung H H, Chen F C. Adv. Electron. Mater., 2018, 4(7): 1700655.
[85]

Park J S, Walsh A. Annu. Rev. Condens. Matter Phys., 2021, 12(1): 95.
[86]

Ochoa-Martinez E, Ochoa M, Ortuso R D, Ferdowsi P, Carron R, Tiwari A N, Steiner U, Saliba M. ACS Energy Lett., 2021, 6(7): 2626.
[87]

Wang J T, Jin G Y, Zhen Q Z, He C Y, Duan Y. Adv. Mater. Interfaces, 2021, 8(9): 2002078.
[88]

Shi B, Xin Y, Hou F, Sheng G, Li Y, Wei C, Yi D, Li Y, Ying Z, Zhang X. J. Phys. Chem. C, 2018, 122: 21269.
[89]

Hoque M N F, He R, Warzywoda J, Fan Z Y. ACS Appl. Mater. Interfaces, 2018, 10(36): 30322.
[90]

Chen Q, Zhou H P, Song T B, Luo S, Hong Z R, Duan H S, Dou L T, Liu Y S, Yang Y. Nano Lett., 2014, 14(7): 4158.
[91]

Emrul K, Hossain C, Kiyoto M, Ryuji K, Said K, Jae-Joon L, Takeshi N, Ashraful I. ACS Energy Lett., 2018, 3: 1584.
[92]

Jacobsson T J, Correa-Baena J P, Halvani Anaraki E, Philippe B, Stranks S D, Bouduban M E F, Tress W, Schenk K, Teuscher J, Moser J E, Rensmo H, Hagfeldt A. J. Am. Chem. Soc., 2016, 138(32): 10331.
[93]

He Y T, Wang W H, Qi L M. ACS Appl. Mater. Interfaces, 2018, 10(45): 38985.
[94]

Son D Y, Lee J W, Choi Y J, Jang I H, Lee S, Yoo P J, Shin H, Ahn N, Choi M, Kim D, Park N G. Nat. Energy, 2016, 1(7): 16081.
[95]

Hawash Z, Raga S R, Son D Y, Ono L K, Park N G, Qi Y B. J. Phys. Chem. Lett., 2017, 8(17): 3947.
[96]

Zhang Y, Zhang C C, Gao C H, Li M, Ma X J, Wang Z K, Liao L S. Sol. RRL, 2019, 3(2): 1604153.
[97]

Zhao W G, Yao Z, Yu F Y, Yang D, Liu S F. Adv. Sci., 2018, 5(2): 1700131.
[98]

Lu J J, Chen S C, Zheng Q D. Sci. China Chem., 2019, 62(8): 1044.
[99]

Klug M T, Osherov A, Haghighirad A A, Stranks S D, Brown P R, Bai S, Wang J T W, Dang X N, Bulović V, Snaith H J, Belcher A M. Energy Environ. Sci., 2017, 10(1): 236.
[100]

Gong X, Guan L, Pan H P, Sun Q, Zhao X J, Li H, Pan H, Shen Y, Shao Y, Sun L J, Cui Z F, Ding L M, Wang M K. Adv. Funct. Mater., 2018, 28(50): 1804286.
[101]

Xu W Z, Zheng L Y, Zhang X T, Cao Y, Meng T, Wu D Z, Liu L, Hu W P, Gong X. Adv. Energy Mater., 2018, 8(14): 1703178.
[102]

Zhang J, Chen R J, Wu Y Z, Shang M H, Zeng Z B, Zhang Y, Zhu Y J, Han L Y. Adv. Energy Mater., 2018, 8(5): 1701981.
[103]

Wang K, Zheng L Y, Zhu T, Yao X, Yi C, Zhang X T, Cao Y, Liu L, Hu W P, Gong X. Nano Energy, 2019, 61: 352.
[104]

Wang Z K, Li M, Yang Y G, Hu Y, Ma H, Gao X Y, Liao L S. Adv. Mater., 2016, 28(31): 6767.
[105]

Wang J T W, Wang Z P, Pathak S, Zhang W, de Quilettes D W, Wisnivesky-Rocca-rivarola F, Huang J, Nayak P K, Patel J B, Mohd Yusof H A, Vaynzof Y, Zhu R, Ramirez I, Zhang J, Ducati C, Grovenor C, Johnston M B, Ginger D S, Nicholas R J, Snaith H J. Energy Environ. Sci., 2016, 9(9): 2892.
[106]

Liu W, Liu N J, Ji S L, Hua H F, Ma Y H, Hu R Y, Zhang J, Chu L, Li X A, Huang W. Nano Micro Lett., 2020, 12(1): 119.
[107]

Wang Z W, Tao J L, Shen J L, Kong W G, Yu Z H, Wang A Y, Fu G S, Yang S P. J. Power Sources, 2021, 488: 229449.
[108]

Bai Y, Dong Q F, Shao Y C, Deng Y H, Wang Q, Shen L, Wang D, Wei W, Huang J S. Nat. Commun., 2016, 7(1): 12806.
[109]

Wu Y Z, Yang X D, Chen W, Yue Y F, Cai M L, Xie F X, Bi E B, Islam A, Han L Y. Nat. Energy, 2016, 1(11): 16148.
[110]

Zhang F, Shi W, Luo J, Pellet N, Yi C, Li X, Zhao X, Dennis T, Li X, Wang S. Adv. Mater., 2017, 29: 1606806.
[111]

Wang R, Xue J, Meng L, Lee J, Yang Y. Joule, 2019, 3: 1464.
[112]

Wang R, Xue J, Wang K, Wang Z, Yang Y. Science, 2019, 366: 1509.
[113]

Chen W, Wang Y F, Pang G T, Koh C W, Djurišić A B, Wu Y H, Tu B, Liu F Z, Chen R, Woo H Y, Guo X G, He Z B. Adv. Funct. Mater., 2019, 29: 1808855.
[114]

Yang S, Dai J, Yu Z H, Shao Y C, Zhou Y, Xiao X, Zeng X C, Huang J S. J. Am. Chem. Soc., 2019, 141(14): 5781.
[115]

Li M G, Yu L S, Zhang Y, Gao H, Li P, Chen R F, Huang W. Sol. RRL, 2020, 4(11): 2000481.
[116]

Song S, Park E Y, Ma B S, Kim D J, Park H H, Kim Y Y, Shin S S, Jeon N J, Kim T S, Seo J. Adv. Energy Mater., 2021, 11(10): 2003382.
[117]

Liu Z Z, Cao F R, Wang M, Wang M, Li L. Angew. Chem. Int. Ed., 2020, 59(10): 4161.
[118]

Wu X, Zhang L, Xu Z, Olthof S, Ren X D, Liu Y C, Yang D, Gao F, Liu S F. J. Mater. Chem. A, 2020, 8(17): 8313.
[119]

Xiong J, Dai Z J, Zhan S P, Zhang X W, Xue X G, Liu W Z, Zhang Z L, Huang Y, Dai Q L, Zhang J. Nano Energy, 2021, 84: 105882.
[120]

Kang D H, Kim S Y, Lee J W, Park N G. J. Mater. Chem. A, 2021, 9(6): 3441.
[121]

Zhang C C, Wang Z K, Yuan S, Wang R, Li M, Jimoh M F, Liao L S, Yang Y. Adv. Mater., 2019: 1902222.
[122]

Hu X F, Wang H X, Wang M, Zang Z G. Sol. Energy, 2020, 206: 816.
[123]

Peng J, Khan J. Adv. Energy Mater., 2018, 8: 1801208.
[124]

Yoo J J, Wieghold S, Sponseller M C, Chua M R, Bertram S N, Hartono N T P, Tresback J S, Hansen E C, Correa-Baena J P, Bulović V, Buonassisi T, Shin S S, Bawendi M G. Energy Environ. Sci., 2019, 12(7): 2192.
[125]

Li M H, Yeh H H, Chiang Y H, Jeng U S, Su C J, Shiu H W, Hsu Y J, Kosugi N, Ohigashi T, Chen Y A, Shen P S, Chen P, Guo T F. Adv. Mater., 2018, 30(30): 1801401.
[126]

Hu Y H, Schlipf J, Wussler M, Petrus M L, Jaegermann W, Bein T, Müller-Buschbaum P, Docampo P. ACS Nano, 2016, 10(6): 5999.
[127]

Chen P, Bai Y, Wang S C, Lyu M Q, Yun J H, Wang L Z. Adv. Funct. Mater., 2018, 28(17): 1706923.
[128]

Jiang Q, Zhao Y, Zhang X W, Yang X L, Chen Y, Chu Z M, Ye Q F, Li X X, Yin Z G, You J B. Nat. Photonics, 2019, 13(7): 460.
[129]

Ahmad S, Fu P, Yu S W, Yang Q, Liu X, Wang X C, Wang X L, Guo X, Li C. Joule, 2019, 3(3): 794.
[130]

Chen P, Bai Y, Lyu M Q, Yun J H, Hao M M, Wang L Z. Sol. RRL, 2018, 2(3): 1700186.
[131]

Stolterfoht M, Caprioglio P, Wolff C M, Márquez J A, Nordmann J, Zhang S S, Rothhardt D, Hörmann U, Amir Y, Redinger A, Kegelmann L, Zu F S, Albrecht S, Koch N, Kirchartz T, Saliba M, Unold T, Neher D. Energy Environ. Sci., 2019, 12(9): 2778.
[132]

Chen P, Bai Y, Wang L Z. Small Struct., 2021, 2(1): 2000050.
[133]

Shao Y C, Yuan Y B, Huang J S. Nat. Energy, 2016, 1(1): 15001.
[134]

Younes E M, Gurung A, Bahrami B, El-Maghraby E M, Qiao Q. Carbon, 2021, 180: 226.
[135]

Seo J, Park S, Chan Kim Y, Jeon N J, Noh J H, Yoon S C, Seok S I. Energy Environ. Sci., 2014, 7(8): 2642.
[136]

Ren G H, Han W B, Deng Y Y, Wu W, Li Z W, Guo J X, Bao H C, Liu C Y, Guo W B. J. Mater. Chem. A, 2021, 9(8): 4589.
[137]

Jeon N, Na H, Jung E, Yang T, Seo J. Nat. Energy, 2018, 3: 682.
[138]

Singh T, Öz S, Sasinska A, Frohnhoven R, Mathur S, Miyasaka T. Adv. Funct. Mater., 2018, 28(14): 1706287.
[139]

Liu C, Yang Y, Ding Y, Xu J, Liu X L, Zhang B, Yao J X, Hayat T, Alsaedi A, Dai S Y. ChemSusChem, 2018, 11(7): 1232.
[140]

Peng J, Duong T, Zhou X, Shen H, Wu Y, Mulmudi H, Wan Y, Zhong D, Li J, Tsuzuki T. Adv. Energy Mater., 2017, 7: 1601768.
[141]

Tavakoli M M, Giordano F, Zakeeruddin S M, Grätzel M. Nano Lett., 2018, 18(4): 2428.
[142]

Chavan R D, Yadav P, Tavakoli M M, Prochowicz D, Nimbalkar A, Bhoite S P, Bhosale P N, Hong C K. Sustain. Energy Fuels, 2020, 4(2): 843.
[143]

Zhou Y Q, Wu B S, Lin G H, Xing Z, Li S H, Deng L L, Chen D C, Yun D Q, Xie S Y. Adv. Energy Mater., 2018, 8(20): 1800399.
[144]

Belisle R A, Jain P, Prasanna R, Leijtens T, McGehee M D. ACS Energy Lett., 2016, 1(3): 556.
[145]

Liang P W, Chueh C C, Williams S T, Jen A K Y. Adv. Energy Mater., 2015, 5(10): 1402321.

Funding

This study was supported in part by the National Natural Science Foundation of China(61704089)

China Postdoctoral Science Foundation(2019M661899)

Jiangsu Planned Projects for Postdoctoral Research Funds(2019K140)

PDF (26684KB)

4344

Accesses

0

Citation

Detail
Sections
Recommended

/

〈 〉

Address of Editorial Office: No. 33 Beisihuan Xilu, Zhongguancun , Beijing 100190, China
Tel: +86 10 8262 7757
Fax: +86 10 8262 7757
E-mail: progchem@mail.las.ac.cn
http://www.progchem.ac.cn
    • 　
    Copyright © Editorial Office of Progress in Chemistry