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Strong Electron–Phonon Coupling and Self-Trapped Excitons in the Defect Halide Perovskites A3M2I9 (A = Cs, Rb; M = Bi, Sb)
Chemistry of Materials ( IF 7.2 ) Pub Date : 2017-04-26 00:00:00 , DOI: 10.1021/acs.chemmater.7b01184 Kyle M. McCall 1 , Constantinos C. Stoumpos 1 , Svetlana S. Kostina 1 , Mercouri G. Kanatzidis 1 , Bruce W. Wessels 1
Chemistry of Materials ( IF 7.2 ) Pub Date : 2017-04-26 00:00:00 , DOI: 10.1021/acs.chemmater.7b01184 Kyle M. McCall 1 , Constantinos C. Stoumpos 1 , Svetlana S. Kostina 1 , Mercouri G. Kanatzidis 1 , Bruce W. Wessels 1
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The optical and electronic properties of Bridgman grown single crystals of the wide-bandgap semiconducting defect halide perovskites A3M2I9 (A = Cs, Rb; M = Bi, Sb) have been investigated. Intense Raman scattering was observed at room temperature for each compound, indicating high polarizability and strong electron–phonon coupling. Both low-temperature and room-temperature photoluminescence (PL) were measured for each compound. Cs3Sb2I9 and Rb3Sb2I9 have broad PL emission bands between 1.75 and 2.05 eV with peaks at 1.96 and 1.92 eV, respectively. The Cs3Bi2I9 PL spectra showed broad emission consisting of several overlapping bands in the 1.65–2.2 eV range. Evidence of strong electron–phonon coupling comparable to that of the alkali halides was observed in phonon broadening of the PL emission. Effective phonon energies obtained from temperature-dependent PL measurements were in agreement with the Raman peak energies. A model is proposed whereby electron–phonon interactions in Cs3Sb2I9, Rb3Sb2I9, and Cs3Bi2I9 induce small polarons, resulting in trapping of excitons by the lattice. The recombination of these self-trapped excitons is responsible for the broad PL emission. Rb3Bi2I9, Rb3Sb2I9, and Cs3Bi2I9 exhibit high resistivity and photoconductivity response under laser photoexcitation, indicating that these compounds possess potential as semiconductor hard radiation detector materials.
中文翻译：
缺陷卤化物钙钛矿中的强电子-声子耦合和自陷激子A 3 M 2 I 9（A = Cs，Rb; M = Bi，Sb）
研究了宽带隙半导体缺陷卤化物钙钛矿A 3 M 2 I 9（A = Cs，Rb; M = Bi，Sb）的Bridgman生长单晶的光学和电子性质。在室温下，每种化合物都观察到强烈的拉曼散射，表明其高极化率和强的电子-声子耦合。对每种化合物都测量了低温和室温光致发光（PL）。Cs 3 Sb 2 I 9和Rb 3 Sb 2 I 9具有在1.75和2.05 eV之间的宽PL发射带，其峰值分别在1.96和1.92 eV处。Cs 3 Bi 2I 9 PL光谱显示宽发射，由1.65–2.2 eV范围内的多个重叠带组成。在PL发射的声子展宽中观察到了与碱金属卤化物相当的强电子-声子耦合证据。从温度相关的PL测量获得的有效声子能量与拉曼峰能量一致。提出了一个模型，其中Cs 3 Sb 2 I 9，Rb 3 Sb 2 I 9和Cs 3 Bi 2 I 9中的电子-声子相互作用诱导小的极化子，导致激子被晶格捕获。这些自陷激子的重组导致广泛的PL发射。Rb 3 Bi 2 I 9，Rb 3 Sb 2 I 9和Cs 3 Bi 2 I 9在激光光激发下表现出高电阻率和光电导响应，表明这些化合物具有作为半导体硬辐射检测器材料的潜力。
更新日期：2017-04-26
中文翻译：
缺陷卤化物钙钛矿中的强电子-声子耦合和自陷激子A 3 M 2 I 9（A = Cs，Rb; M = Bi，Sb）
研究了宽带隙半导体缺陷卤化物钙钛矿A 3 M 2 I 9（A = Cs，Rb; M = Bi，Sb）的Bridgman生长单晶的光学和电子性质。在室温下，每种化合物都观察到强烈的拉曼散射，表明其高极化率和强的电子-声子耦合。对每种化合物都测量了低温和室温光致发光（PL）。Cs 3 Sb 2 I 9和Rb 3 Sb 2 I 9具有在1.75和2.05 eV之间的宽PL发射带，其峰值分别在1.96和1.92 eV处。Cs 3 Bi 2I 9 PL光谱显示宽发射，由1.65–2.2 eV范围内的多个重叠带组成。在PL发射的声子展宽中观察到了与碱金属卤化物相当的强电子-声子耦合证据。从温度相关的PL测量获得的有效声子能量与拉曼峰能量一致。提出了一个模型，其中Cs 3 Sb 2 I 9，Rb 3 Sb 2 I 9和Cs 3 Bi 2 I 9中的电子-声子相互作用诱导小的极化子，导致激子被晶格捕获。这些自陷激子的重组导致广泛的PL发射。Rb 3 Bi 2 I 9，Rb 3 Sb 2 I 9和Cs 3 Bi 2 I 9在激光光激发下表现出高电阻率和光电导响应，表明这些化合物具有作为半导体硬辐射检测器材料的潜力。
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