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首页> 外文期刊>Energy & environmental science >Intrinsic femtosecond charge generation dynamics in single crystal CH3NH3PbI3
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Intrinsic femtosecond charge generation dynamics in single crystal CH3NH3PbI3

机译：单晶CH3NH3PbI3中本征飞秒电荷产生动力学

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Hybrid metal-organic perovskite solar cells have astounded the solar cell community with their rapid rise in efficiency while maintaining low-cost fabrication. The intrinsic material photophysics related to the generation of free charges, their dynamics and efficiency, however, remains to be understood. As fabrication techniques improve, larger crystal grain sizes have been shown to be a critical factor for improving both the optical and transport properties of the hybrid metal halide perovskites. In this work, we use pulses of multi-THz frequency light in the ultra-broadband 1-30 THz (4-125 meV) range to observe the ac conductivity in large single crystal CH3NH3PbI3. Our spectra reveal the ultrafast dynamics and efficiencies of free charge creation and extremely high charge carrier mobility as high as 500800 cm(2) V-1 s(-1). While quasi-equilibrium analysis of efficiencies through the Saha equation suggests a binding energy on the order of 49 meV, an observed reflectance feature appearing at high pump fluence occurs at 12 meV and is consistent with an orbital transition of the exciton, indicating a much lower Rydberg energy of 17 meV at room temperature. The signature of the exciton is found to vanish on a 1 ps time scale commensurate with the appearance of mobile carriers, consistent with thermal dissociation of the exciton to the continuum in the room temperature tetragonal phase.
机译：混合金属有机钙钛矿太阳能电池的效率迅速提高，同时又保持了低成本制造，这震惊了太阳能电池社区。然而，与自由电荷的产生，它们的动力学和效率有关的内在物质光物理仍有待了解。随着制造技术的改进，较大的晶粒尺寸已显示出是改善杂化金属卤化物钙钛矿的光学和传输性能的关键因素。在这项工作中，我们使用在超宽带1-30 THz（4-125 meV）范围内的多THz频率的光脉冲来观察大型单晶CH3NH3PbI3中的交流电导率。我们的光谱揭示了超快速的动力学和自由电荷产生的效率以及极高的载流子迁移率，高达500800 cm（2）V-1 s（-1）。虽然通过Saha方程对效率进行的准平衡分析表明结合能约为49 meV，但在高泵浦注量下出现的观察到的反射特征出现在12 meV处，并且与激子的轨道跃迁相一致，表明其低得多。室温下里德伯格能量为17 meV。发现激子的签名在1 ps的时间尺度上消失，与移动载体的出现相称，这与激子在室温四方相中热解离成连续体相一致。

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