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

Abstract

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.