3D nanographene precursor suppress interfacial recombination in PEDOT: PSS based perovskite solar cells

Decreasing the number of interfacial defect states and enhancing the charge transfer ability of charge transport layers have become promising strategies for increasing the efficiency and stability of perovskite solar cells (PSCs). In this study, we used a holistic interface strategy, employing three-dimensional (3D) triphenylamine-based nanographene (NG) precursors with well-defined molecular structures and presenting various functional units (F, Br, and OMe), to achieve efficient inverted PSCs. The 3D NG precursor formed a bridge between the perovskite film and the poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) hole transport layer (HTL) with minimized interfacial defect states, while also passivating defect states at the bulk perovskite through automatic bottom-up passivation. Computational simulations and experimental findings revealed that the functional groups of the 3D NG precursors anchored the perovskites through the formation of strong F···Pb, Br···Pb, and OMe···Pb coordination bonds. Through these synergetic properties, inverted PSCs delivered great enhancements in their photovoltaics performance characteristics, with the improvement in absolute efficiency exceeding 3 %. This new practical approach toward interfacial engineering of inverted PSCs appears to enhance their PCEs and thermal, light soaking, and long term stabilities.