High-Efficiency All-Ambient Air, All-Solution and Low-Temperature Processed Nonfullerene Photovoltaics with Layer-by-Layer Co-Doped Polymeric Anodes

Abstract

Nonfullerene organic photovoltaics (OPVs) have achieved breakthrough with pushing the power conversion efficiency exceeding 15%. While this shed light on OPV commercialization, the high cost associated to the scalable device fabrications remains a giant challenge. Herein, we reported an all-air, all-solution and low-temperature processed OPV that yielded 12.24% efficiency with impressive fill factor of 0.73, which was mostly attributed to the usages of high-merit polymeric anodes and modified active blends. The design principle toward the high-merit anodes is to induce a heavy acid doping, make a large removal of insulating and hydrophilic components in whole matrices, and restrain the formation of large-domain aggregates. A unique layer-by-layer co-doping was thus developed and it enabled a stable polymeric anode with record-high trade-off between optical transmittance and electrical conductivity. Besides, solvent vapor annealing was proposed to boost device efficiency and it has the advantages of finely adjusting the active blend morphology and raising the electron mobility. As a consequence, the unprecedented device with high efficiency was obtained and it maintained most (~92.3%) of the initial efficiency after 60 day storage. This work gives the bright future for cost-effective all-solution processed OPVs prepared in air ambient at low temperatures.

Keywords: organic photovoltaics, all-solution processing in air, layer-by-layer doping, PEDOT:PSS, stability