Stephen Forrest, advisor

The unique properties of organic semiconductors have led to significant scientific and commercial interest in organic electronics over the last ten years. During that time, these devices have gone from being a laboratory curiosity to being in millions of pants pockets around the world. Going forward, there are opportunities for organic photovoltaics (OPVs) to provide carbon-neutral energy production due to the potential for flexible, low-cost, and large-scale production.
In this defense, I present my developments in tandem OPVs for high-efficiency photovoltaics. By incorporating multiple sub-cells into a multi-junction OPVs architecture, the losses inherent in all OPV devices can be reduced significantly. Two of the works presented incorporate one solution-processed and one vacuum-processed sub-cell, resulting in efficiencies as high as 7.8±0.3\% power conversion efficiency. We have also developed new techniques to utilize two solvent-processed sub-cells into a monolithic tandem architecture, leading to a > 10% increase in power conversion efficiency compared to an optimized single-cell device.