Interfacial Modification of NiOx for Highly Efficient and Stable Inverted Perovskite Solar Cells

Nickel oxide is one of the most promising hole-transporting materials in inverted perovskite solar cells (PSCs) but suffers from undesired reactions with perovskite which leads to limited device performance and stability. Self-assembled monolayers (SAMs) are demonstrated to effectively optimize the NiOx/perovskite interface, but the significance of the compactness of the SAM at the interface is less investigated. Here, a series of methoxy-substituted triphenylamine functionalized benzothiadiazole (TBT) based SAM molecules, TBT-BA, TBT-FBA, and TBT-DBA, with benzoic acid, 2-fluorobenzoic acid and isophthalic acids as anchoring groups are used to modify NiOx. TBT-BA with the simplest structure is demonstrated to form the densest SAM on NiOx, thus optimized NiOx/SAM/perovskite interface is achieved with enhanced charge collection and suppressed interfacial reaction and recombination. TBT-BA can also passivate the perovskite most effectively due to the highest binding energy toward perovskite, thus the corresponding inverted PSCs show the highest PCE of 24.8% and maintain 88.7% of the initial PCE after storage at 60 degrees C for 2635 h in the glovebox. The work provides important insights into designing SAM molecules for modification transporting layers for efficient and stable PSCs.