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. [ABSTRACT FROM AUTHOR]