Impact of alloy-like phase on energy loss mitigation in multi-component organic photovoltaics

The multi-component strategy has proven effective in advancing the performance of organic photovoltaics(OPVs),enhancing photocurrent andfill factor through spectral complementarity and morphology optimization.However,the open-circuit voltage(VOC)mechanism in multi-component systems lacks systematic investiga-tion.In this study,we explore the influence of alloy-like phases on energy level distribution and energy loss mechanisms in multi-component OPVs.Appropriate modulation of donor alloy-like phases maintains the original intermolecular stack-ing,enhances component compatibility,reduces acceptor aggregation,and improves acceptor phase purity,mitigating non-radiative recombination losses.Additionally,suitable alloy-like phase modulation elevates charge transfer(CT)states,reducing the gap between CT and local exciton state,lowering reorganization energy,and alleviating radiative recombination loss below the bandgap.Through synergistic optimization(layer-by-layer method with solid additive),ternary devices based on Y6 acceptor achieve a notable 19.41%power conversion efficiency,offering new insights for the analysis of the energy loss of the multi-component OPVs.

Alloy-like ternary polymer solar cells with over 17.2% efficiency

Ternary strategy has been considered as an efficient method to achieve high performance polymer solar cells(PSCs). A power conversion efficiency(PCE) of 17.22% is achieved in the optimized ternary PSCs with10 wt% MF1 in acceptors. The over 8% PCE improvement by employing ternary strategy is attributed to the simultaneously increased JSCof 25.68 mA cm^-2, VOCof 0.853 V and FF of 78.61% compared with Y6 based binary PSCs. The good compatibility of MF1 and Y6 can be confirmed from Raman mapping, contact angle,cyclic voltammetry and morphology, which is the prerequisite to form alloy-like state. Electron mobility in ternary active layers strongly depends on MF1 content in acceptors due to the different lowest unoccupied molecular orbital(LUMO) levels of Y6 and MF1, which can well explain the wave-like varied FF of ternary PSCs. The third-party certified PCE of 16.8% should be one of the highest values for single bulk heterojunction PSCs. This work provides sufficient references for selecting materials to achieve efficient ternary PSCs.