Inhibition of buried cavities and defects in metal halide perovskite photodetectors via a two-step spin-coating method

The performance of perovskite photodetectors (PPDs) is sensitive to the quality of their perovskite films. Solution-processed perovskite films suffer from excess lead halide and irregular nanocavities located at the buried interface, which result in a high dark current density and hinder the improvement of the PPD performance. Herein, we could govern the perovskite growth by introducing the modulating MAI molecule in the PbI2 precursor in a modified two-step spin-coating method. Consequently, we obtained a high-quality (large grain size, pinhole-free and well-packed) perovskite layer with uniform thickness. Also, we fabricated a photodiode-type PPD with a p-i-n configuration. At a reverse bias of -1.5 V, the optimum PPD achieved a high specific detectivity of up to 5 x 10(11) Jones and a decent responsivity of 0.79 A W-1 under 532 nm laser irradiation with a light intensity of 1 mu W cm(-2). Meanwhile, it exhibited a fast response of 2.6 mu s and 72.8 mu s for the rise and fall times, respectively. This strategy enriches the approaches for preparing high-quality perovskite films for diverse perovskite optoelectronic devices.