Metal Halide Perovskite Light Sources for On-chip Applications



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Metal halide perovskites have attracted much attention as economical gain materials for light emitting diodes (LEDs) and on-chip lasers in photonic integrated circuits. However, the potential commercialization of these perovskite light sources has been hindered by the lack of a systematic approach to overcome perovskite instability, and in the case of lasers, the challenge to directly pattern perovskites into resonators. The goals for this dissertation are to establish systematic approaches to stabilize perovskites, and to demonstrate economical perovskite lasers. To understand the importance of the abovementioned goals, the requirements and fundamentals of on-chip light sources are first discussed. Next, a detailed study of the degradation mechanisms in perovskites is presented. Perovskites degrade by exposure to high temperature, ambient atmosphere, polar solvents (e.g., water), and high photo-/e-beam energy which are used in conventional lithography (e.g., photo-/e-beam lithography). Because of the instability of perovskites, we face not only the short shelf life of perovskite devices, but also the difficulty in the direct patterning of perovskites into an optical cavity. In order to improve the shelf life of perovskite devices, a practical encapsulation method as well as its comparison to other common encapsulation methods are presented. To create laser cavities, a novel direct-patterning method of perovskite — nanoimprint lithography — is presented. We show that nanoimprint lithography improves the quality of perovskites and explain the mechanism behind the positive effects of nanoimprint lithography. With a synergistic approach which includes a practical encapsulation method, an efficient patterning method that also improves material morphology, and a high-quality cavity design, the first demonstration of quasi-CW lasing from directly patterned perovskites is shown. Finally, future directions for improving the efficiency of optically pumped perovskite lasers and the realization of electrically pumped perovskite lasers are discussed.



Light sources, Perovskite materials