In‐Situ Hot Oxygen Cleansing and Passivation for All‐Inorganic Perovskite Solar Cells Deposited in Ambient to Breakthrough 19% Efficiency

Abstract

AbstractAll‐inorganic perovskite CsPbI3 has attracted extensive attention recently because of its excellent thermal and chemical stability. However, its photovoltaic performance is hindered by large energy losses (Eloss) due to the presence of point defects. In addition, hydroiodic acid (HI) is currently employed as a hydrolysis‐derived precursor of intermediate compounds, which often leads to a small amount of organic residue, thus undermining its chemical stability. Herein, an in‐situ hot oxygen cleansing with superior passivation (HOCP) for the triple halide‐mixed CsPb(I2.85Br0.149Cl0.001) perovskite solar cells (abbreviated as CsPbTh3) deposited in an ambient atmosphere to reduce the Eloss to as low as 0.48 eV for the power conversion efficiency (PCE) to reach 19.65% is demonstrated. It is found that the hot oxygen treatment effectively removes the organic residues. Meanwhile, it passivates halide vacancies, hence reduces the trap states and nonradiative recombination losses within the perovskite layer. As a result, the PCE is increased significantly from 17.15% to 19.65% under 1 sun illumination with an open‐circuit voltage enlarged to 1.23 from 1.14 V, which corresponds to an Eloss reduction from 0.57 to 0.48 eV. Also, the HOCP‐treated devices exhibit better long‐term stability. This insight should pave a way for decreasing nonradiative charge recombination losses for high‐performance inorganic perovskite photoelectronics.