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-1PbnBr3n+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 degrees C (CH)2PbBr4 (n = 1) to 304 degrees C (CH)2(MA)3Pb4Br13. The RP perovskites (CH)2(MA)n-1PbnBr3n+1 (n = 1-4) demonstrated sharp exciton emission peaks from blue (similar to 408 nm) to green (similar to 528 nm). The Xray 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)3Pb4Br13 (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)3Pb4Br13 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)2Pb3Br10 (n = 3) and (CH)2(MA)Pb2Br7 (n = 2) in ambient temperature.