Multifunctional Passivation of Pb/I Defect Sites and Carrier Dynamics Optimization Based on Femtosecond Laser Beat Effect

Abstract As promising optoelectronic materials, lead halide perovskites (LHP) have been widely studied for their outstanding optoelectronic properties. However, the formation of halide vacancies (V X ) and uncoordinated metallic lead atoms (Pb 0 ) by ion migration, and consequent instability and nonradiative complexation, hinders their practical applications. Here, a femtosecond laser beat effect‐assisted multifunctional passivation (FsBEAMP) approach is proposed to address these issues. Utilizing the beat effect of femtosecond laser pulses, a multifunctional passivation is achieved, which passivated the iodine vacancies (V I ) and Pb 0 simultaneously. For the FsBEAMP‐processed samples, the hysteresis effect has been greatly reduced due to suppression of iodide ions migration. The 3‐fold increase in PL intensity and 7‐fold prolongation of carrier lifetime have been achieved due to multifunctional passivation effect and enhanced absorption caused by the periodic structure, allowing enhanced light‐coupling effect. As a result, a 4‐fold enhancement in responsivity and external quantum efficiency, along with a robust detectivity of 2.5 × 10 12 Jones, has been realized for the FsBEAMP‐processed photodetector. It is noted that the detectivity remains 97% after a month in an ambient environment. This work will significantly contribute to the perovskite photonics and optoelectronics by providing a highly efficient way for multifunctional passivation of LHP.