Yu Shaohua, Xu Jin, Shang Xiaoying, Ma En, Lin Fulin, Zheng Wei, Tu Datao, Li Renfu, Chen Xueyuan
CAS Key Laboratory of Design and Assembly of Functional Nanostructures, State Key Laboratory of Structural Chemistry, and Fujian Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Adv Sci (Weinh). 2021 Oct;8(19):e2100084. doi: 10.1002/advs.202100084. Epub 2021 Aug 11.
Understanding the origin of temperature-dependent bandgap in inorganic lead-halide perovskites is essential and important for their applications in photovoltaics and optoelectronics. Herein, it is found that the temperature dependence of bandgap in CsPbBr perovskites is variable with material dimensionality. In contrast to the monotonous redshift ordinarily observed in bulk-like CsPbBr nanocrystals (NCs), the bandgap of 2D CsPbBr nanoplatelets (NPLs) exhibits an initial blueshift then redshift trend with decreasing temperature (290-10 K). The Bose-Einstein two-oscillator modeling manifests that the blueshift-redshift crossover of bandgap in the NPLs is attributed to the significantly larger weight of contribution from electron-optical phonon interaction to the bandgap renormalization in the NPLs than in the NCs. These new findings may gain deep insights into the origin of bandgap shift with temperature for both fundamentals and applications of perovskite semiconductor materials.
了解无机铅卤化物钙钛矿中与温度相关的带隙起源对于其在光伏和光电子学中的应用至关重要。在此，发现CsPbBr钙钛矿中带隙的温度依赖性随材料维度而变化。与通常在块状CsPbBr纳米晶体（NCs）中观察到的单调红移相反，二维CsPbBr纳米片（NPLs）的带隙在温度降低（290 - 10 K）时呈现出先蓝移后红移的趋势。玻色 - 爱因斯坦双振子模型表明，NPLs中带隙的蓝移 - 红移交叉归因于电子 - 光学声子相互作用对NPLs中带隙重整化的贡献权重比NCs中显著更大。这些新发现可能为钙钛矿半导体材料的基础研究和应用中带隙随温度变化的起源提供深入见解。
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