Low Energy Manufacturing and Optimization of Perovskite Film Growth for Application in Wire-Shaped Photodetection

This thesis aims to develop a deeper understanding of perovskite thin film growth and stability for integration into photodetectors for mechanoluminescent sensing applications. Photodetectors play an important role in our society, acting as the sensing mechanism for most remotes, switches, triggers, and indicators. As new thin-film semiconducting materials are synthesized, the volumetric footprint of photodetectors decreases to opens doors for multi-functional materials such as wearable electronics and sensor integrated composites. The recent synthesis of methylammonium lead halide perovskite has triggered a renaissance due to being solution processable and high performing at relatively low fabrication cost. The optoelectronic properties of perovskite are strongly dependent on the crystalline quality and morphology of the film. Uniform temperature strongly affects nucleation and grain growth rate, which dictate the morphology, uniformity, coverage, and quality of the perovskite layer. A novel heating method was developed in an effort to gain uniform temperature control during the perovskite annealing and deposition process. This novel method was applied to carbon nanotube yarns (CNYs), which resulted in the successful fabrication of flexible wire-shaped photodetectors. The CNY perovskite photodetectors produced a competitive detectivity (1.76 x 1011 Jones), on/off ratio (45), and response time (0.132 s), but suffered instability due to the perovskite’s reaction to high temperatures and moisture. Thin-film growth dynamics of the more stable ‘triple cation’ perovskite (TCP) (Cs0.05(FA100-xMAx)0.95Pb(I1-xBrx)3) were studied which revealed crystallinity could be improved through the tuning of both the organic cation and halide sites. The transition toward scalable fabrication methods was made by studying the material’s behavior towards anti-solvent bath crystallization. It was revealed that the use of diethyl ether would lower the annealing temperature, which resulted in thermally stable, phase pure, high quality, large grain thin films. Photodetectors were fabricated using the optimized TCP, which showed stability towards temperatures of 85° C for up to 10 hours with an extremely rapid response time of 12.4 μs. Finally, a model predicting TCP film quality as a function of annealing time and temperature was developed to calculate ideal annealing conditions for future commercial and scientific applications.