Wan et al
[14] synthesized two chlorinated two-dimensional fused-ring electron acceptors, C8T-BDT4Cl and C8T-BDSe4Cl, using benzodithiophene (BDT) and benzoselenophene (BDSe) substituted with alkylthiophene as the central donor unit. Ultimately, the device based on C8T-BDSe4Cl:PM6 achieved a PCE of 13.5% due to its higher
JSC (21.79 mA/cm
2), surpassing the 12.2% PCE of the C8T-BDT4Cl:PM6 device. Li et al
[15] synthesized a multi-fused ring molecule IDTIDSe-IC using indeno[6-b']dithienoindeno[5-b']diselenophene as the backbone. Without any additives, the device based on IDTIDSe-IC and J51 achieved a PCE of 8.02%,
VOC of 0.91 V,
JSC of 15.16 mA/cm
2, and FF of 58.0%. Liu et al
[16] synthesized three A-D-A structured acceptor materials, SeCT-IC, CSeT-IC, and CTSe-IC, using the same electron-deficient end group A unit and different selenophene-containing central core D units. Ultimately, the device based on J71:CTSe-IC achieved a PCE of 11.59%, higher than that of J71:SeCT-IC (10.89%) and J71:CSeT-IC (8.52%). Lin et al
[17] synthesized isomeric ladder-type non-fullerene acceptors SRID-4F and TRID-4F by replacing sulfur with selenium in π-conjugated backbones. The device based on PBDB-T-2F:SRID-4F achieved a PCE of 13.05%, while devices based on PBDB-T-2F:TRID-4F and PBDB-T-2F:IT-4F achieved PCEs of 12.33% and 12.63%, respectively. Lanbanti et al
[18] synthesized two NFA molecules, SeOut and SeIn, by replacing sulfur atoms at the outer or inner positions of the central core with selenium atoms, and then synthesized two additional NFA molecules, SeOutMe and SeInMe, by attaching methyl chains to the terminal groups. Ultimately, the SeOutMe device exhibited excellent operational stability. After 450 hours of operation, its PCE remained at 95% of the initial value, with a half-life reaching 5600 hours, compared to only 400 hours for the ITIC device. Wang et al
[19] designed a new central core selenopheno[2-b]thiophene and synthesized a narrow bandgap non-fullerene acceptor SeTIC, followed by synthesizing SeTIC4Cl through chlorination of the end group. Ultimately, the device based on PM6:SeTIC4Cl achieved a PCE of 13.32%, higher than the device based on PM6:SeTIC (7.46%). Additionally, it was found that when the active layer thickness increased from 100 nm to 300 nm, the PCE showed good tolerance. Ge et al
[20] used indeno[2',
3':
4,
5]thieno[3,2-
b]selenophene as the central core and synthesized two non-fullerene acceptors TSeIC-M-Cl and TSeIC-P-Cl with mono-chlorinated (2,3-dihydro-3-oxo-1H-inden-1-ylidene)propanedinitrile at different positions as end groups. Ultimately, the device based on PBT1-C:TSeIC-P-Cl achieved a PCE of 11.26%, outperforming the PCE of the device based on PBT1-C:TSeIC-M-Cl (9.72%). Wan et al
[21] synthesized three near-infrared absorbing non-fullerene small molecular acceptors BDSeIC, BDSeIC2Br, and BDSeIC4Br, using benzo[5-b']diselenophene as the central core and mono-bromo or di-bromo substituted 2-(2,3-dihydro-3-oxo-1H-inden-1-ylidene)propanedinitrile as end groups. Without any treatment, the device based on PM6:BDSeIC2Br achieved a high PCE of 11.9%. After thermal annealing, a PCE of 12.05% and
Eloss of 0.64 eV were obtained. Zhang et al
[22] synthesized two non-fullerene small molecular acceptors (NF-SMAs) TSeIC4Cl and TSeIC4Br using indeno[2',
3':
4,
5]thieno[2-b]selenophene as the central core and di-chlorinated and di-brominated end groups. Ultimately, the polymer solar cell based on PM6:TSeIC4Br exhibited higher
JSC,
Voc, and FF, achieving a photoelectric conversion efficiency (PCE) of 12%. Wan et al
[23] used benzo[5-b']diselenophene as the central core and synthesized three FREAs, BDSe-4Cl, BDSe-2(BrCl), and BDSe-4Br, with dichloro IC, hybrid dihalogenated IC (IC-BrCl), and dibromo IC, respectively. Ultimately, PCEs of 13.82%, 13.12%, and 14.54% were achieved based on BDSe-4Cl:PM7, BDSe-4Br:PM7, and BDSe-2(BrCl):PM7, respectively. Wan et al
[24] used benzo[5-b']diselenophene as the central core and synthesized two NFSMAs, BDSeThCl and BDSePhCl, using IC with a 2-chlorothiophenyl end group and IC with a mono-chlorinated phenyl end group. The device based on BDSePhCl:PM7 achieved a PCE of 13.68% with a relatively low energy loss of only 0.49 eV, while the device based on BDSeThCl achieved a PCE of 11.91% and
VOC of 0.97 eV. Liu et al
[25] used indeno[2',
3':
4,
5]thieno[2-b]selenophene as the central core unit and non-halogenated thiophene as the terminal group to synthesize an A-D-A structured non-fullerene small molecular acceptor TSeTIC. Ultimately, the TA-treated PM6:TSeTIC device achieved a PCE of 13.71% with lower photovoltaic cell loss (
Eloss) (0.60 eV), surpassing the 12.05% PCE and 0.64 eV
Eloss of the PM6:TTTIC device. Liang et al
[26] used selenophene as the π bridge to connect the indenodithiophene (IDT) core with 3-(dicyanomethylene)indan-1-one (IC) or difluorinated IC (2F-IC) end groups, synthesizing two non-fullerene acceptors IDT2Se and IDT2Se-4F. The device based on IDTSe-4F achieved a PCE of 11.19%. Liu et al
[27] used thiophene, selenophene, and thieno[2-b]thiophene as π bridges to connect the IDTO central core unit with electron-withdrawing IC-2F end groups, synthesizing three narrow-band non-fullerene acceptors IDTO-T-4F, IDTO-Se-4F, and IDTO-TT-4F. The device based on PBDB-T:IDTO-T-4F ultimately achieved a PCE of 12.62%, with a high
VOC of 0.864 V, a high
JSC of 20.12 mA/cm
2, and an FF of 72.7%. Zhang et al
[28] used selenophene to connect the alkylated indeno[6-b']dithiophene (IDT) central core with 1,1-dicyanomethylene-3-indanone (ICs) end groups having 0~2 fluorine substitutions, synthesizing three non-fullerene acceptors IDT2SeC2C4, IDT2Se-C2C4-2F, and IDT2Se-C2C4-4F. The device based on PBDB-T:IDT2Se-C2C4-4F mixture achieved a PCE of 10.57%. Tang et al
[29] designed and synthesized three asymmetric A-D-A type non-fullerene acceptors (MQ3, MQ5, and MQ6). The device based on PM6:MQ6 achieved a PCE of 16.39%,
VOC of 0.88 V, FF of 0.7566, and
JSC of 24.62 mA/cm
2. Li et al
[30] replaced one thiophene in indodithiophene (TPT) with selenophene, developing a new asymmetric selenium-substituted central core SePT, which was then coupled with 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]naphthalen-1-ylidene)propanedinitrile to synthesize an asymmetric A-D-A structured non-fullerene acceptor SePT-IN. When mixed with PBT1-C, the device based on SePT-IN achieved a PCE of 10.20%, surpassing the device based on TPT-IN (8.91%). Liu et al
[31] synthesized three A-D-A type non-fullerene acceptors T-Se, T-Se-4F, and T-Se-Th using three different end groups based on an asymmetric selenium-containing central core. Solar cells based on PM6:T-Se-4F and PM6:T-Se-Th achieved
JSC of 18.09 and 16.90 mA/cm
2,
VOC of 0.781 and 0.912 V, FF of 66.6% and 66.8%, and PCE of 9.41% and 10.29%, respectively. Cao et al
[32] designed and synthesized an asymmetric seven-ring electron-donating core (DTPPSe) and synthesized three new non-fullerene electron acceptors DTPPSe-IC, DTPPSe-2F, and DTPPSe-4F with varying numbers of fluorine atoms substituted on the end groups. The OSCs based on PBDB-T:DTPPSe-2F had a PCE of 13.76%,
JSC of 22.16 mA/cm
2, and FF of 73.70%, outperforming the OSCs based on PBDB-T:DTPPSe-IC and PBDB-T:DTPPSe-4F (9.88% and 12.03%). Li et al
[33] designed and synthesized two asymmetric selenium-substituted non-fullerene electron acceptors SePTT-2F and SePTTT-2F with different conjugated backbones. The OSCs based on PBT1-C:SePTTT-2F achieved a PCE of 12.24%, surpassing the PCE of the OSCs based on SePTT (10.9%).