Quantifying charge transportation for stable organic solar cells with a novel aluminum acetylacetone electron collection layer

Abstract

Elucidating charge transportation mechanism for low-temperature solution-processed charge collection layer is crucial for efficient and stable organic solar cells (OSCs). Herein, we present a facile method to fabricate Al(acac)3 film and integrate it as electron collection layer (ECL) in OSCs. The PM6:Y6-based OSCs with Al(acac)3 ECL achieve a higher efficiency of 16.12% as compared to the control devices with a 10.90% efficiency. Importantly, the Al(acac)3-based devices present superior operational stability, which retains 60% of the initial PCE after 100 h continuous illumination in air. Investigations on optics and carrier recombination dynamics reveal that the improved performance benefits from high up to 98% transparency of Al(acac)3 ECL, optimized interfacial contact and enhanced exciton dissociation ratio from 85.10% to 97.51%. Further studies on quantified interface resistances during the internal charge transfer indirectly reflect the enhancement of stability. These results highlight the promising prospect of Al(acac)3 ECL in processing compatible, operationally stable high efficiency OSCs.