UC San Diego

The ascent of perovskite photovoltaics has been one of the most significant and exciting developments in renewable energy research. The myriad of absorber composition blends and compatible device structures offer a wide variety of applications and several paths towards full commercial deployment. However, the rapid decrease in performance of perovskite photovoltaics under operational conditions prohibits their ubiquitous distribution.

In this dissertation, a top to bottom approach is utilized to advance the commercial viability of perovskite photovoltaics. Beginning with encapsulation schemes, large-area graphene stacks with a polyisobutylene edge seal were investigated as potential moisture and oxygen barriers for perovskite films. These materials were found to provide a moderate but insufficient protection from a damp heat environment. However, an all-glass encapsulation scheme enabled over 1000 hours of exposure to damp heat (85 ◦C, 65% RH) without any loss in film quality (validated by photoluminescence, UV-Vis spectroscopy, and X-ray diffraction). Attention was then focused on the selective contact layers, beginning with a presentation of electrochemical measurements that were adapted to study the optoelectronic properties, surface coverage, and reactivity of transport layers. Tin oxide, commonly used as an electron transport layer in perovskite photovoltaics, was highlighted as a case study to demonstrate the screening potential of these tools by correlating cyclic voltammetry on a bottom selective contact to final device performance once the device stack was completed. Chronoamperometry was also used to test the reactivity of tin oxide, at the surface, to acidic perovskite precursors, which can potentially be used to predict the reactivity of perovskites at buried interfaces within a device. Next, a solvent-free dry transfer process was designed and highlighted for its ability to deposit a large, uniform film of conjugated polymers which are frequently used as hole transport layers in perovskite photovoltaics. This technique is especially useful for top selective contacts since it eliminates concerns with solvent compatibility of the underlying perovskite film. Lastly, design considerations of the absorber were comprehensiviely explored through the development of a high throughput Perovskite Automated Solar Cell Assembly Line which was used, in combination with active learning principles, to design and test wide bandgap perovskite absorbers for use in silicon-perovskite tandem photovoltaics. Overall, this dissertation presents the steps that we have taken to advances perovskite photovoltaics from an intriguing research project to an effective and vital technology that aid in addressing the ever increasing global energy demands.