18.01% Efficiency organic solar cell and 2.53% light utilization efficiency semitransparent organic solar cell enabled by optimizing PM6:Y6 active layer morphology

Optimizing the photoactive layer morphology is a simple, promising way to improve the power conversion efficiencies (PCEs) of organic solar cells (OSCs). Here, we compared different post-processing treatments on PM6:Y6 blend films and relevant effects on device performances, including as-cast, thermal annealing and solvent annealing. This solvent annealing processes can effectively improve the vertical distribution and aggregation of polymer donors and small molecule acceptors, then optimize the active layer film morphology, ultimately elevating PCE. Thus, one of champion efficiencies of 18.01% was achieved based on the PM6:Y6 binary OSCs. In addition, a relatively high light utilization efficiency (2.53%) was achieved when a transparent electrode made of Cu(1 nm) and Ag (15 nm) was utilized to fabricate a semitransparent OSC with a remarkable PCE of 13.07% and 19.33% average visible-light transmittance. These results demonstrated that carefully optimizing morphology of active layer is conducive to achieving a high-performance OSC.