Observation of Unusual Optical Band Structure of CH3NH3PbI3 Perovskite Single Crystal,ACS Photonics

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Observation of Unusual Optical Band Structure of CH3NH3PbI3 Perovskite Single Crystal
ACS Photonics ( IF 6.5 ) Pub Date : 2018-02-27 00:00:00 , DOI: 10.1021/acsphotonics.8b00033
Wei Huang _{1,

2} , Shizhong Yue _{1,

2} , Yu Liu _{1,

2} , Laipan Zhu _{1,

3} , Peng Jin _{1,

2} , Qing Wu _{1,

2} , Yang Zhang _{1,

2} , Yanan Chen _{1,

2} , Kong Liu _{1,

2} , Ping Liang ₁ , Shengchun Qu _{1,

2} , Zhijie Wang _{1,

2} , Yonghai Chen _{1,

2}

Affiliation

Extensive efforts have been undertaken on the photoelectric physics of hybrid organolead halide perovskites to unveil the reason for the attractive photovoltaic performance. Yet, the resulting evidence is far from being fully conclusive. Herein, we provide another direct support for this issue. In addition to the observation on the conventional band edge at 1.58 eV that presents a blueshift toward temperature increase, interestingly, we also observe an unusual optical band edge at 1.48 eV in CH₃NH₃PbI₃ perovskite single crystals for the first time. Contrary to the conventional band edge, this one shows an obvious redshift toward the enhancement in temperature, in agreement with the Varshni relation. More interestingly, the unusual band edge exhibits a series of obvious absorption and photocurrent signals, but the according photoluminescence signals are not observable. This indicates that this band edge is particularly beneficial for the photovoltaic effect due to the inhibited radiative recombination. The kinetics on photoinvolved charge transition and transfer are investigated using the pump–probe photoconductivity technique, and a changeable band structure model is proposed.

中文翻译：

CH ₃ NH ₃ PbI ₃钙钛矿单晶异常光带结构的观察

杂化有机铅卤化钙钛矿的光电物理方面已进行了广泛的努力，以揭示具有诱人的光伏性能的原因。然而，由此产生的证据远非完全定论。在此，我们为这个问题提供了另一个直接的支持。除了观察到在1.58 eV处的常规能带边缘呈现向温度升高的蓝移之外，有趣的是，我们还在CH ₃ NH ₃ PbI _3中观察到了在1.48 eV处的异常光学带边缘。钙钛矿单晶。与常规的带边缘相反，这一带显示出明显的向温度升高的红移，这与Varshni关系一致。更有趣的是，异常的频带边缘表现出一系列明显的吸收和光电流信号，但是无法观察到相应的光致发光信号。这表明该带边缘由于抑制了辐射复合而特别有利于光伏效应。利用泵浦-探针光电导技术研究了光涉及的电荷跃迁和转移的动力学，并提出了一个可变的能带结构模型。

更新日期：2018-02-27

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