Scalable Deposition of Solution-Processed Thin Film Photovoltaics and Organic Light Emitting Diodes

Organic and perovskite-based materials promise disruption to the field of thin film optoelectronics, owing to their advantages of low-cost, lightweight, flexibility, and spectral tuning compared to tradition solid-state bulk electronics. However, the high power conversion efficiencies of thin film photovoltaics (12% for organic and 22% for perovskite-based) and some high resolution organic light emitting diodes (OLEDs) displays are developed with lab-scale processes.

This dissertation focuses on the development of innovative and scalable fabrication processes for solution-processed thin film photovoltaics and OLEDs. The entire ecosystem of thin films processing is developed with an emphasis on aerosol-based processes. In Part 1, this dissertation elucidates the in-flight aerosols for thin film deposition, followed by its implementation in the demonstration of concurrently pumped ultrasonic spray coating to quickly and precisely optimize archetypal polymer photovoltaic materials. Next, organic LEDs are fabricated with a direct write aerosol process from non-toxic inks, attaining high resolution 140 ppi RGB displays. In Part 2, this knowledge is used for the concurrent optimization of high performance diketopyrrolopyrrole organic photovoltaics with 6.5% efficiency, and perovskite photovoltaics with 15.4% efficiency. At the time of their publication, these results were the highest reported spray coated device efficiencies for both technologies. The spraying technique enabled elucidation of carrier collection dynamics in thick devices, further employed in establishing design rules for thin film photovoltaics with inexpensive but non-reflective carbon-based electrodes. In Part 3, multi-step procedures are developed to determine non-hazardous solvent systems for both organic and perovskite-based high performance thin film photovoltaics. While the topics span a broad set of research, this dissertation pushes the field one step closer to the commercial uptake of solution processed thin film optoelectronic.