Photophysics of halide perovskites

抄録

Recently, lead halide perovskites debuted in the field of condensed matter physics and materials chemistry, and they are a new class of semiconductor materials for a wide range of applications such as photovoltaics, photodetectors, light-emitting diodes, and lasers. High-quality thin films and nanocrystals can be easily synthesized by simple low-temperature solution processes. Grains in polycrystalline thin films and nanocrystals possess extremely low-density defect states, and they exhibit high photoluminescence quantum yields even at room temperature. Defect-tolerant halide perovskites show complex and fascinating optical and transport properties reflecting their unique ionic crystal structures. We determined the multi-band electronic structure, exciton binding energy, and reduced exciton mass of halide perovskites by using nonlinear optical spectroscopy [1-3] and magneto-optical spectroscopy [4]. The multi-level electronic structure originating from a large spin–orbit interaction was also revealed by optical Stark spectroscopy of nanocrystals [5]. Strong exciton-phonon coupling causes unique optical and thermal properties [6-8]. Furthermore, nanocrystal quantum dots and atomically thin two-dimensional layers of lead halide perovskites show the superior luminescence properties. Bright nanocrystals display highly efficient single-photon emission [9], and trions and biexcitons cause photoluminescence blinking [10]. Stable spin-polarized excitons in two-dimensional layers show ultrafast expansion at room temperature [11]. In this talk, we discuss the fundamental optical properties of lead halide perovskites and the photocarrier dynamics in perovskite solar cell devices. We also discuss the impact of the surface and interface states on the optical and transport properties of halide perovskite materials and solar cell devices.

Part of this work was supported by JSPS KAKENHI (Grant No. JP19H05465) and JST-CREST (Grant No. JPMJCR21B4).

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