Diamine tailored smooth and continuous perovskite single crystal with enhanced photoconductivity

Two-dimensional diamine-based perovskites are now attracting intense interest due to their enhanced ambient stability as compared to monoamine-based perovskites. Few reports to date have focused on the fundamental morphology of diamine-based perovskite single crystals and related this to their electrical properties and the further photoconductivity behaviors. Herein, we systematically investigated pentamethylenediammonium lead bromide (PDAPbBr4) and pentylammonium lead bromide (PA2PbBr4) perovskite single crystals, and explored how their morphology and structure characteristics affected their electrical properties and photodetecting performances. Notably, PDAPbBr4 perovskite exhibited distinctive smooth and continuous morphology, quite different from the rough and discontinuous morphology of PA2PbBr4 perovskite. Besides, the single organic interlayer spacer in PDAPbBr4 perovskite induced an orderly arrangement of inorganic sheets and decreased interlayer distance. With smooth, continuous morphology and shortened interlayer distance, PDAPbBr4 perovskite exhibited lower defect density and higher electrical conductivity than PA2PbBr4 perovskite. Importantly, a PDAPbBr4-based photodetector produced a responsivity of 7.92 mA W−1, a photocurrent on/off ratio of 246, and response time of 31 ms, which outperformed a PA2PbBr4-based photodetector by 387 times in responsivity, 27 times in on/off ratio, and 10 times in response time. The findings might provide a foundation for understanding the morphology characteristics of 2D perovskites and the effects on their optoelectronic performance.