Dual-face single and tandem absorber layer photodetectors based on Li-doped halide perovskite with enhanced optoelectrical properties

Metal halide perovskite photodetectors (PDs) offer strong optoelectronic potential; however, their performance is often limited by interfacial losses and trap-mediated charge recombination. Here, we demonstrate a simple and effective lithium iodide (LiI) incorporation strategy to simultaneously regulate film microstructure, suppress trap states, and optimize charge transport in methylammonium lead iodide (MAPbI₃)-based photodetectors. The controlled introduction of Li⁺ ions markedly enhances ultraviolet–visible light absorption while preserving the intrinsic optical bandgap, leading to improved film coverage and crystalline quality. Steady-state photoluminescence measurements reveal a pronounced reduction in trap density, evidenced by a stable emission peak centered near ~ 770 nm. As a result, the optimized devices achieve a high responsivity of 512.58 mA W⁻¹ and a detectivity of 5.06 × 10¹¹ Jones. Importantly, systematic device architecture analysis reveals that photodetectors employing a single MAPbI₃ absorber layer exhibit superior current–voltage characteristics due to reduced interfacial resistance and more efficient charge carrier transport. This work provides clear mechanistic insight into the dual role of lithium incorporation and interface engineering, offering a scalable pathway for enhancing the performance and reliability of perovskite-based photodetectors for advanced optoelectronic applications.