NCTU Nanophotonics

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Perovskite lasers

Solution processable optoelectronic materials are fascinated for their great capabilities in the cost-effective and large-scale manufacturing in optoelectronics devices. Among the tremendous research efforts conducted during in the last two years, the hybrid organic-inorganic metal-halide perovskites now show the photovoltaic power conversion efficiency approaching 18 % and long-range balanced electron-hole transport distances. More interestingly, the solution-processed perovskite films recently have shown promising photoluminescence quantum efficiencies ex-ceeding 70 % and the wavelength-tunable lasing performance in hybrid perovskite films with different halides, making them a promising candidate for the applications in efficient light emit-ting diodes (LEDs) and on-chip coherent light sources. Therefore numerous studies which focused on the excitonic properties, recombination lifetimes, optical absorbance, and carrier mobilties, have been made to investigate the specific material properties in the perovskite films, revealing the optoelectronic processes accompanied with established theoretical models.

Hybrid organic-inorganic perovskites are intrinsically complex materials. The existence of various crystalline structures or phase states at different ambient temperatures may cause intricate interactions between structural disorders, resulting in different materials properties and optical characteristics. From the previous experiments and theoretical studies, the fundamental CH3NH3PbX3 (X: Cr, Br, or I) halide structures are basically built of the organic (CH3NH3)+ cat-ion and (PbX3)- inorganic anion. The versatility of the organic part affords the possibility of fine tuning material properties, thus affecting the optical performance of different peroveskites. For example, the optical spectra of engineered lead halide organic-inorganic perovksites can be eas-ily tailored by varying the organic cation, giving a great improvement of the optical efficiencies and fine tuning of the emission wavelengths. Also, self-assembled layered perovskite struc-tures have recently shown enhanced nonlinear optical properties in microcavities. Recently, we investigate the relation between the phase-transition of the perovskite thin films and the lasing mechanism at different phase states. It may provide further studies on the perspectives of future lasing and lighting industries.