The solar cells that are integrated in the building itself are an enticing energy pathway to utilize a large area for solar energy and while achieving a high building energy-efficiency. However, this effort is hampered by the need for mounting tradition photovoltaic (PV) cells in the built environment due to the cost and architectural impediments. The development of light weight and flexible solar cells that are transparent can address this problem. This project will perform research that will lead to the development of transparent PV. Specifically this project will utilize the excitonic character of small-bandgap molecules and organic semiconductors that leads to "oscillator bunching" to produce selectively near-infrared harvesting. The transparent PV architectures with power production from infrared photons alone have the potential to exhibit theoretical and practical efficiencies of 35% and 21%, respectively, while leaving the visible part of the spectrum completely unaffected.
Intellectual merit: In this project, the foundation for the transparent solar cell will be crystal-orientation-controlled and nanostructured donor-acceptor hetero-junction blends integrating near-infrared excitonic semiconductors of small-molecules and J-aggregating molecules, which can be utilize to capture 650-1200 nm wavelength infrared light. Routes to tailoring the crystalline ordering, orientation, and microstructure of neat layer and blends will be established to realize the connection between morphology and the photo-physical response to maximize the exciton harvesting. To guide experiments, photo-carrier generation and photoconduction using multi-dimension morphological, optical-field, and electrical device simulations will be modeled and incorporated into a framework for evaluating the efficiency, transparency, and color rendering to assure full optimization for window integration.
Broader impacts: Transparent PVs have potential to impact the US energy production and building energy utilization by reducing the energy cost for PV deployment, reducing cooling demand, and imparting a net-negative carbon footprint. To complement the research work, the PI will establish a coordinated outreach and educational effort by (1) organizing workshops, (2) working with a local-area museum, (3) advising student-run initiative to retrofit buildings with renewable energy solutions, and (4) supporting students from under-represented groups.
