Triphenylamine-Polystyrene Blends for Perovskite Solar Cells with Simultaneous Energy Loss Suppression and Stability Improvement

Energy loss induced by nonradiative recombinations plays a critical role in determining power conversion efficiencies in perovskite solar cells, whereas device stability impacts their long-time reliability in the ambient environment. It is an important challenge to suppress energy loss and improve device stability simultaneously. Herein, an interfacial layer of triphenylamine (TPA):polystyrene (PS) blend coated on the hybrid perovskite layer to concurrently suppress energy loss and improve device stability is reported. The energy loss is suppressed from 0.49 to 0.35 eV by passivating surface defects in hybrid perovskites via Lewis acid-base interactions with the combination of electron-donating aromatic nucleus in PS and tertiary amine in TPA, leading to perovskite solar cells with a high open-circuit voltage of 1.18 V, a fill factor of about 80%, and a power conversion efficiency of 22.1%. Meanwhile, the device stability in the ambient environment is improved significantly by the TPA:PS blend due to its superior hydrophobicity which is suggested by its high contact angle of 91.1 degrees as compared to 64.0 degrees for the pristine perovskite film. Herein, an efficient interfacial engineering approach with the TPA:PS blend to suppress energy loss and improve device stability simultaneously towards realistic applications is demonstrated.