Enhanced Performance in Quasi-Two-Dimensional Perovskite Photodetectors by Controlling the Formation of a Large N-Phase

Quasi-two-dimensional (2D) Ruddlesden-Popper perovskites (general formula A₂B_<i>n</i>-1Pb_<i>n</i>X_3<i>n</i>+1) have received extensive attention in the field of photoelectric detection due to their tunable optical band gap and excellent stability. However, the prepared 2D perovskite films are generally composed of samples with different n values. With the increase of <i>n</i>, the photoelectric performance is improved due to the decreased binding energy, but the thermodynamic stability is decreased. Therefore, it is necessary to find a method that can simultaneously promote the formation of a large <i>n</i>-value perovskite and improve its stability. In this work, we fabricated a photodetector based on the typical quasi-2D perovskite BA₂MAPb₂I₇ (<i>n</i> = 2) and promoted the formation of a large <i>n</i>-phase quasi-2D perovskite in BA₂MAPb₂I₇ by slowing down its recrystallization rate of perovskite through adding a metal-organic framework (ZIF-8) solution on the top of the BA₂MAPb₂I₇ layer. Concurrently, the organic ligands present in ZIF-8 effectively passivated the defects in BA₂MAPb₂I₇ and enhanced its stability. The obtained photodetectors show a high detection rate of 1.03 × 10¹³ Jones, a high responsiveness of 0.925 A/W, a high switching ratio of 10⁵, and excellent long-term operating stability, light stability, and environmental stability without packaging. This work provides a feasible way to further improve the photoelectric performance and stability of quasi-2D perovskites.