In this article, photoluminescence (PL) behaviors of inorganic cesium lead bromide (CsPbBr₃) nanosheets are investigated in a broad temperature range from 5 to 500 K. As can be seen from the temperature evolution of the PL peak position, the bandgap blueshift induced by thermal lattice expansion is found to be gradually compensated by the bandgap redshift caused by electron–phonon coupling for the temperature variation from 5 K to 360 K. As the temperature is further increased, the nearly completely compensated PL peak position turns to exhibit a rapid blueshift, again at ∼360 K. Such turning behavior is consistent with an orthorhombic–tetragonal (γ–β) phase transition at this critical temperature. For the PL linewidth, it shows a continuous broadening at temperatures beyond 40 K, suggesting the dominant role of phonon scattering, especially at high temperatures. These findings of temperature dependent photophysical properties of CsPbBr₃ nanosheets may provide useful information of their further applications in the emerging nano photo-electronic devices.

中文翻译：

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溴化铯铯钙钛矿纳米片中的热膨胀，电子-声子耦合和相变的光致发光特征

本文研究了无机铯溴化铅（CsPbBr ₃）的光致发光（PL）行为。）在5至500 K的宽温度范围内研究了纳米片。从PL峰位置的温度演变可以看出，发现由热晶格膨胀引起的带隙蓝移逐渐被电子引起的带隙红移所补偿。 –声子耦合，可在5 K至360 K的温度范围内变化。随着温度的进一步升高，几乎完全补偿的PL峰值位置再次显示出快速的蓝移，再次在〜360 K处发生。这种转向行为与正交晶相一致–在此临界温度下发生四方（γ–β）相变。对于PL线宽，它在超过40 K的温度下显示出连续变宽的现象，这表明声子散射起主要作用，尤其是在高温下。这些与温度相关的CsPbBr光物理性质的发现₃纳米片可提供其在新兴纳米光电器件中进一步应用的有用信息。