A Multifunctional LiF as Passivated Material for an Efficient and Stable Perovskite Photodetector

Metal cation and halide anion defects in perovskite films play a pivotal role in determining the performance and stability of perovskite photodetectors. In this study, LiF was utilized as a passivation material, both doped into the perovskite bulk phase and applied as a passivation layer on the top surface of the perovskite film. LiF forms hydrogen bonds and strong ionic interactions with perovskites, effectively passivating lattice and surface defects. Furthermore, as an insulator, LiF suppresses bimolecular and defect-assisted recombination, thereby enhancing carrier mobility and device stability. The optimized LiF-passivated MAPbI_3-<i>x</i>Br_<i>x</i> perovskite photodetector achieved an external quantum efficiency (EQE) of up to 87.5%, a maximum detectivity of 4.48 × 10¹³ Jones, and a theoretical linear dynamic range of 157.52 dB. Remarkably, the device retained 82% of its EQE after 2400 h of maximum power point tracking.