Effect of polymer molecular weight on J51 based organic solar cells

Very recently, organic solar cells (OSCs) have achieved outstanding scientific results with a power conversion efficiency (PCE) of over 16%. However, it is rarely reported on how molecular weight (M_n) of polymer donors affects the solar cell performances. In this work, the wide bandgap polymer donor J51 with different M_n from 8 to 36 kDa were synthesized and used for fabrication of J51:PC₇₁BM devices. It was found that the PCEs were gradually on the increase with the increased molecular weight of J51 donor. This work demonstrated the relationship between devices performance and polymer molecular weight, which enriched the OSCs research content. It provides valuable reference information that optimal molecular weight of polymer donors should be limited in what is considered the applicable range.