Controlled fabrication of semiconductor nanostructures with unique physicochemical properties is vital for future technologies. In this study, transformation from red‐emitting metal halide perovskite CH₃NH₃PbI₃ nanocrystals (NCs) to green‐emitting CH₃NH₃PbBr₃ NCs was achieved without significant morphological changes and loss of photoluminescence (PL) efficiency via a controlled halide exchange reaction. In situ single‐particle PL imaging along with detailed structural and elemental characterizations revealed that sudden cooperative transitions between two light‐emitting states via intermediate dark states with >100 s durations during halide exchange originate from two distinct defect‐mediated reconstruction processes with different activation energies (0.072 and 0.40 eV), leading to an isokinetic temperature of ca. 314 K, across a solid‐state miscibility gap between the I‐ and Br‐rich phases inside a single NC.

中文翻译：

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原位钙钛矿纳米晶体上形态和效率保持卤化物交换过程中结构转变的原位探索

具有独特的物理化学性质的半导体纳米结构的受控制造对于未来技术至关重要。在这项研究中，从红色发光的金属卤化物钙钛矿CH ₃ NH ₃ PbI ₃纳米晶体（NCs）到绿色发光的CH ₃ NH ₃ PbBr ₃转变通过受控的卤化物交换反应，可以实现无明显形态变化和光致发光（PL）效率损失的NCs。原位单粒子PL成像以及详细的结构和元素表征表明，在卤化物交换过程中，通过中间暗态（持续时间超过100 s），两个发光态之间的突然协作转变起因于具有不同活化能的两个不同的缺陷介导的重建过程（0.072和0.40 eV），导致等速运动温度约为。在单个NC内富I和富Br相之间的固态混溶间隙中达到314K。