Ultrafast Laser Irradiation Induced Oxidation of Dopant-Free Spiro-OMeTAD for Improving the Perovskite Solar Cells Performance

The exceptional photoelectric performance and high compatibility of perovskite materials render perovskite solar cells highly promising for extensive development, thus garnering significant attention. In perovskite solar cells, the hole transport layer plays a crucial role. For the commonly employed organic small molecule hole transport material Spiro-OMeTAD, a certain period of oxidation treatment is required to achieve complete transport performance. However, this posttreatment oxidation processes typically rely on ambient oxidation, which poses challenges in terms of precise control and leads to degradation of the perovskite light absorption layer. This approach fails to meet the demands for high efficiency and stability in practical application. Herein, the mechanism of ultrafast laser on Spiro-OMeTAD and the reaction process for laser-induced oxidation of it are investigated. PbI₂ at Perovskite/Spiro-OMeTAD interface breaks down to produce I₂ upon ultrafast laser irradiation and I₂ promote the oxidation process. Through the laser irradiation oxidation processing, a higher stability of perovskite solar cells is achieved. This work establishes a new approach toward oxidation treatment of Spiro-OMeTAD.