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Monday, August 5, 2019

Mixed-halide perovskite synthesis by chemical reaction and crystal nucleation under an optical potential

Md Jahidul Islam, Ken-ichi Yuyama, Kiyonori Takahashi, Takayoshi Nakamura, Katsuaki Konishi & Vasudevanpillai Biju

The development of new methods to engineer lead halide perovskite crystals with a controlled band gap and emission properties is an active subject in materials science and chemistry. We present the preparation of mixed-halide lead perovskites by spatially- and temporally- controlled chemical reactions and crystal growth under an optical potential in unsaturated precursor solutions. The crystals are characterized by transmission and photoluminescence spectral measurements and X-ray diffraction analysis. When compared with the spontaneous formation of multiple crystals in saturated precursor solutions, the optical potential creates large single crystals with a high chloride composition, providing distinct blue and green fluorescent crystals of chloride–bromide lead perovskites. We discuss the formation of mixed-halide perovskites from the viewpoints of an increased rate of chemical reaction via the formation and desolvation of precursor complexes and a decreased free energy potential.

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