Prolonging the exciton diffusion length by manipulating molecular stacking enables pseudo-planar heterojunction organic solar cells to achieve over 19% efficiency

A solid additive, SA-5F, is employed to promote molecular stacking, which leads to higher crystallinity, boosting the exciton diffusion coefficient and then exciton diffusion length. Thus, D18/Y6+-based PPHJ OSCs afford an impressive PCE of 19.11%.