Reducing oxygen vacancies of MoO3 by polyaniline functionalization for stable and efficient inorganic tri-brominated perovskite solar cells

The photovoltaic performance of perovskite solar cells (PSCs) is closely dependent on the efficient carrier extraction and transport at the interface. Here, a polyaniline (PANI) functionalized MoO3 (PANI/MoO3) hole transport material (HTM) is exploited to perfect the interface between the perovskite layer and carbon electrode in all-inorganic CsPbBr3 PSCs. After functionalization with PANI, the p-type behavior and the hole mobility and conductivity of MoO3 are improved by reducing the oxygen vacancies, which boosts the hole extraction and transport, energy level arrangement at the interface of CsPbBr3 perovskite/(PANI/MoO3) HTM. Meanwhile, the PANI/MoO3 with rich C–N and N–H groups introduced by PANI passivates the ions trap states of perovskite films by the C–N⋯Pb2+ (Cs+) Lewis acid-base coordination and the N–H⋯Br− hydrogen bonding, leading to an effective suppression of non-radiative recombination for improved carrier extraction. As a result, the PANI/MoO3 HTMs-based CsPbBr3 PSCs obtain a remarkably increased power conversion efficiency of 10.41 %, in comparison with the efficiency of the original device (6.55 %). In addition, the unencapsulated device with PANI/MoO3 HTMs shows excellent long-term stability with 93.9 % maintenance of the initial efficiency after storing in air with 85 % relative humidity and at 85 °C for 30 days. Through reducing the oxygen vacancies of MoO3 by PANI functionalization, a PANI/MoO3 composite with high p-type behavior is fabricated and employed as a hole extractor to boost hole extraction and transport, interface energy level alignment and passivate the surface defects of perovskite film, which helps the all-inorganic CsPbBr3 PSCs achieve a champion PCE up to 10.41 % and excellent humidity-heat stability. [Display omitted] •The PANI functionalization induced OV decrease of MoO3 improves its p-type behavior.•The use of PANI/MoO3 enhances hole extraction and interface energetics alignment.•The healing effect of PANI/MoO3 on CsPbBr3 film defects reduces charge recombination.•The unsealed device achieves a best PCE of 10.41 % and high humidity-heat stability.