Ternary organic solar cells enjoy both the enhanced light absorption by incorporating multiple organic materials in tandem solar cells and the simplicity of processing conditions that are used in single bulk heterojunction solar cells.

We report a trap-assisted photomultiplication (PM) phenomenon in solution-processed polymer photodetectors (PPDs) based on P3HT:PC₇₁BM as the active layer, the maximum EQE of 16,700% is obtained for the PPDs with PC₇₁BM doping weight ratio of 1%. The PM phenomenon is attributed to the enhanced hole tunneling injection assisted by trapped electrons in PC₇₁BM near Al cathode, which can be demonstrated by the transient photocurrent curves and EQE spectra of PPDs with different PC₇₁BM doping ratios. The positive effect of trapped electrons in PC₇₁BM near Al cathode on the hole tunneling injection is further confirmed by the simulated optical field and exciton generation rate distributions in the active layer and the EQE spectra of PPDs with Al(1)/P3HT:PC₇₁BM(100:1)/Al(2) device structure under forward and reverse biases. This discovery may open a new road for organic materials to be used in highly sensitive photodetectors while preserving the advantages of organic materials.

Non-fullerene polymer solar cells (PSCs) attract more attention due to the constantly refreshed power conversion efficiency (PCE) based on the versatile non-fullerene acceptors. In this work, PCEs of 10.51% and 11.02% were obtained for two kinds of non-fullerene PSC with IDT6CN-M or ITCPTC as the acceptor and PBDB-T as the donor. ITCPTC has a relatively narrow bandgap and a high absorption coefficient compared with IDT6CN-M, which explains well the relatively large short-circuit current density of 17.44 mA cm⁻² for the ITCPTC based binary PSCs. Meanwhile, the IDT6CN-M based binary PSCs exhibit a relatively high fill factor (FF) of 75.3% and an open-circuit voltage of 0.915 V. A PCE of 11.92% and a FF of 76.5% were achieved for the ternary PSCs with 60 wt% ITCPTC content in the acceptors, which should be attributed to the enhanced photon harvesting and their good compatibility for a synergistic improvement of exciton utilization and charge transport in the ternary active layers. The FF of 76.5% is among the top values of ternary non-fullerene PSCs.

Twenty percentage efficiency of Cs-substituted perovskite solar cells fabricated by vacuum co-evaporation exhibits superior stability even after storage for one year.