Refined molecular microstructure and optimized carrier management of multicomponent organic photovoltaics toward 19.3% certified efficiency

Abstract

Intuitive nanoscale visualization of sensitive donor–acceptor (D–A) heterojunction interfaces is still a huge challenge in organic photovoltaics (OPVs) but plays a critical role in carrier management. Herein, nanoscale visualization of the interfaces of newly developed asymmetric non-fullerene acceptors (NFAs) with an ideal absorption edge is realized and some interesting molecular microstructural features, including the alloy-like symbiosis of two NFAs in one domain and curved-crystal behavior in the D:A blend, are uncovered and further correlated with the charge transport and non-radiative loss properties in binary and ternary systems. It is also unveiled that for wide bandgap donor and narrow bandgap acceptor systems, the interfacial bending energy obtained on the ionization potential side is negatively correlated with non-radiative loss in small driving force systems, another factor in manipulating energy loss. Finally, double-channel recombination suppression leads to a record efficiency of 19.3% (certified: 19.3%) for asymmetric acceptor-based quaternary OPVs. This work brings interface research into a new era that enables the discovery of intrinsic interfacial features at under sub-nanometer resolution, thus facilitating intrinsic correlations between molecular microstructure and carrier management.