Large negative thermo-optic coefficients of a lead halide perovskite
Large negative thermo-optic coefficients of a lead halide perovskite
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DOI：
10.1126/sciadv.aax0786
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发表时间：
2019-07
期刊：
影响因子：
13.6
通讯作者：
Taketo Handa;H. Tahara;T. Aharen;Y. Kanemitsu
中科院分区：
文献类型：
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作者：
Taketo Handa;H. Tahara;T. Aharen;Y. Kanemitsu
CH3NH3PbCl3的非常规热光响应使相移补偿器和可调缓速器用于可见光。卤化铅钙钛矿是一种很有前途的高性能光子器件半导体。由于折射率决定了半导体器件的最佳设计和性能极限，因此折射率及其对外部调制的变化是先进光子应用中最关键的特性。本文报道了卤化物钙钛矿CH3NH3PbCl3的折射率随温度的升高而明显降低，即具有较大的负热光系数，这与传统无机半导体相反。通过使用这个负系数，我们证明了在传统半导体中发生的热诱导光学相移的补偿。此外，我们观察到CH3NH3PbCl3在光照射过程中折射率变化大而缓慢，并通过理论分析阐明了其热导率非常低的原因。CH3NH3PbCl3的巨大热光响应促进了可见光的有效相位调制。
Unconventional thermo-optic responses of CH3NH3PbCl3 enable phase-shift compensators and tunable retarders for visible light. Lead halide perovskites are promising semiconductors for high-performance photonic devices. Because the refractive index determines the optimal design and performance limit of the semiconductor devices, the refractive index and its change upon external modulations are the most critical properties for advanced photonic applications. Here, we report that the refractive index of halide perovskite CH3NH3PbCl3 shows a distinct decrease with increasing temperature, i.e., a large negative thermo-optic coefficient, which is opposite to those of conventional inorganic semiconductors. By using this negative coefficient, we demonstrate the compensation of thermally induced optical phase shifts occurring in conventional semiconductors. Furthermore, we observe a large and slow refractive index change in CH3NH3PbCl3 during photoirradiation and clarify its origin to be a very low thermal conductivity supported by theoretical analysis. The giant thermo-optic response of CH3NH3PbCl3 facilitates efficient phase modulation of visible light.