Quaternary blends with double cascading charge transport pathways reaching 17.40% efficiency in single-layered organic photovoltaics

Abstract

Double cascading energy level alignment is achieved in bulk heterojunction organic solar cells ensuring efficient carrier splitting and transport. This affords unique advantages in optimizing light absorption, exciton splitting, carrier transport, and charge transfer state energy levels in quaternary blends. Solar cell device power conversion efficiency up to 17.40%, the highest in single layered devices, was achieved. The optimization of the electronic structure and morphology resulted in a simultaneous improvement of the open circuit voltage, short circuit current and fill factor. The proper ancillary donor/acceptor material choice provides useful handles in thin film. Control of the electronic structure and charge transfer state energy level is achieved with the choice of donor and acceptor materials, allowing the manipulation of the hole-transfer rates, carrier transport, and non-radiative recombination losses. A detailed structure-property relationship that best manifests the impo