High-performance semitransparent organic solar cells based on sequentially processed heterojunction

Average visible transmittance (AVT) and power conversion efficiency (PCE) are the two key parameters to evaluate the performance of semitransparent organic solar cells (ST-OSCs). Reducing the donor content can decrease the light absorption in the visible region and increase the AVT values of ST-OSCs. However, minor donor phase is not sufficient for exciton generation, exciton dissociation and charge transport, and limits the PCEs of OSCs. In this work, ST-OSCs based on a sequentially processed heterojunction (SHJ) structure were fabricated. Through sequentially spin-coating donor PM6 as the bottom layer and acceptor Y6 as the top layer, a better vertical phase distribution is formed in the SHJ structure compared with that in the traditional bulk heterojunction (BHJ) structure. At a PM6: Y6 ratio of 1 : 2, the ST-OSCs based on the SHJ structure show a PCE of 12.6% at an AVT of 25.4%, while the BHJ ST-OSCs show a PCE of 11.8% at an AVT of 22.9%.