Nanostructured Ruddlesden–Popper-Layered Lead Bromide Perovskites with Stable and Selected Wavelength for Photodetection Applications

Success in photovoltaic power generation has raised a huge possibility in metal halide perovskites to exhibit excellent photodetection performance with the same physics of photocarrier generation, and their collection at terminal electrodes is employable with less defect-assisted carrier recombination loss. To test this, nanostructured Ruddlesden–Popper (RP)-layered perovskite series were synthesized based on a cyclic organic moiety and Br – halide, resulting in (CH) 2 (MA) n −1 Pb n Br 3 n +1 [where CH─2-(1-cyclohexenyl) ethylamine, MA─methylammonium, Br─bromine, and n = 1–4], to explore how best its mono-to-few layer ( n ) 2D and quasi 2D-structures can offer photodetection performance with maximum absorbance in the unexplored blue-to-green band gap RP perovskites with maximum stability. Thermogravimetric analysis revealed that the very stable nature of these RP perovskites is accompanied by a linear rise in the structural phase transition temperatures, which range from 270 °C (CH) 2 PbBr 4 ( n = 1) to 304 °C (CH) 2 (MA) 3 Pb 4 Br 13 . The RP perovskites (CH) 2 (MA) n −1 Pb n Br 3 n +1 ( n = 1–4) demonstrated sharp exciton emission peaks from blue (∼408 nm) to green (∼528 nm). The X-ray diffraction results confirmed the highly crystalline nature of quasi-2D perovskite thin films. Layer-dependent photoluminescence studies exhibit strong room-temperature exciton photoluminescence and high carrier lifetime. The transient photocurrent measurements for (CH) 2 (MA) 3 Pb 4 Br 13 ( n = 4) RP perovskite thin films show nearly six times the bias voltage changed from 1 to 5 V at 405 nm laser light excitation. In addition, with respect to performance, the (CH) 2 (MA) 3 Pb 4 Br 13 photodetector has shown the highest responsivity (67.2 mA/W), ultrafast transient photocurrent response (122 nA), and high EQE (20.6%) as compared to (CH) 2 (MA) 2 Pb 3 Br 10 ( n = 3) and (CH) 2 (MA)Pb 2 Br 7 ( n = 2) in ambient temperature.