Self-assembly monolayers manipulate the power conversion processes in organic photovoltaics

Surface modification of zinc oxide (ZnO) plays a crucial role in enhancing the performance of organic photovoltaics (OPVs) due to its structure defect. Herein, methoxyphenylphosphonic acid (MPPA) modifier is introduced for interface engineering to improve the cell performance. The power conversion efficiency (PCE) of 11% has been achieved based on fullerene-free systems together with a breakthrough in current density. We obtain ZnO with reduced surface defect and lower work function after incorporation of MPPA modifier. Moreover, by analyzing dynamics process of solar cells, we discover MPPA modifier promotes the exciton generation, exciton diffusion, exciton dissociation and charge transport with reduced bimolecular recombination and trap-based recombination loss, leading to better power conversion processes.