Molecular dispersion enhances quasi-bilayer organic solar cells

In the last couple of years, organic solar cells (OSCs) based on non-fullerene (NF) acceptors have demonstrated tremendous progress in power conversion efficiency (PCE). The majority of state-of-the-art OSCs in the lab is based on the so-called bulk heterojunction (BHJ) architecture consisting of a photoactive layer in blend of an electron donor and acceptor. The presence of numerous microscopic p-n junctions in BHJs enables sufficient surface areas where charge separation occurs, so that the photocurrent and PCE are increased. The device characteristics in BHJ-OSCs are critically affected by the nanostructure or morphology of BHJ films, featuring interpenetrating and continuous networks with domain sizes ideally comparable to the exciton diffusion length.