Mixed Dimethylammonium/Methylammonium Lead Halide Perovskite Crystals for Improved Structural Stability and Enhanced Photodetection

The solvent acidolysis crystallization technique is utilized to grow mixed dimethylammonium/methylammonium lead tribromide (DMA/MAPbBr(3)) crystals reaching the highest dimethylammonium incorporation of 44% while maintaining the 3D cubic perovskite phase. These mixed perovskite crystals show suppression of the orthorhombic phase and a lower tetragonal-to-cubic phase-transition temperature compared to MAPbBr(3). A distinct behavior is observed in the temperature-dependent photoluminescence properties of MAPbBr(3) and mixed DMA/MAPbBr(3) crystals due to the different organic cation dynamics governing the phase transition(s). Furthermore, lateral photodetectors based on these crystals show that, at room temperature, the mixed crystals possess higher detectivity compared to MAPbBr(3) crystals caused by structural compression and reduced surface trap density. Remarkably, the mixed-crystal devices exhibit large enhancement in their detectivity below the phase-transition temperature (at 200 K), while for the MAPbBr(3) devices only insignificant changes are observed. The high detectivity of the mixed crystals makes them attractive for visible-light communication and for space applications. The results highlight the importance of the synthetic technique for compositional engineering of halide perovskites that governs their structural and optoelectronic properties.

Automated summary

The solvent acidolysis crystallization technique is used to grow mixed DMA/MAPbBr(3) crystals, with the highest dimethylammonium incorporation of 44%. These mixed perovskite crystals exhibit lower phase-transition temperature and suppression of the orthorhombic phase compared to MAPbBr(3). The temperature-dependent photoluminescence properties of the mixed crystals are different from MAPbBr(3) due to different organic cation dynamics. The mixed-crystal devices show higher detectivity and significant enhancements below the phase-transition temperature.