Researchers Fabricate Hybrid Organic/Semiconductor Solar Cell
University of Delaware researchers affiliated with the NSF-funded Engineering Research Center (ERC) for Quantum Energy and Sustainable Solar Technologies (QESST), which is headquartered at Arizona State University, have fabricated a proof-of-concept hybrid organic/semiconductor solar cell. Power efficiencies up to 5% have been maintained for several days.
This project advances solar cell technology in several important ways; it also illustrates the advantage of simple processing and high efficiency, the use of lower-cost silicon substrates, and low-cost local manufacture without toxic by-products. Further, because of simplicity of the fabrication, requiring only module fabrication, the technology can be rapidly scaled.
Technological advances include understanding how organic layers on a semiconductor impact surface recombination; development of organic layers that have low surface recombination and increased stability over time (because the organic layer does not participate in carrier collection and the solar cell structure is insensitive to interface defects, stability issues are greatly reduced); development of a functional organic coating that achieves surface band bending in the semiconductor; the ability to achieve large surface band bending to demonstrate a carrier-selective contact, thus increasing both “ideal” and experimental solar cell efficiencies; and demonstration of a high open-circuit-voltage organic-silicon hybrid solar cell.
A fundamental innovation is the development of a carrier-selective contact (CSC) structure using organic layers to induce surface inversion and surface passivation. The general solar cell structure consists of silicon with the organic layer deposited on the surface; silicon serves to absorb light and transport carriers to the junction, induced by the application of the organic layer (see figure). The cells consist of benzoquinone passivation on n-type Si and PEDOT:PSS conductive organic layers.