This work focuses on developing novel chalcogen polymers to synthesize nanocrystals and crystalline thin films for printed photovoltaics applications. We have invented new polymers that consist primarily of linear chains of sulfur or selenium atoms. To our knowledge, polymeric materials with this chalcogen backbone structure have not been previously demonstrated and therefore, there are many opportunities for important discoveries within this field. Specifically, this work has utilized these polymers to develop routes for solution-processing metal-chalcogenide materials in ways that were previously impossible. Chalcopyrite materials such as CuInSxSe2-x (CISSe), the gallium alloy variant CuInxGa1-xSySe2-y (CIGSSe), and the earth-abundant kesterite material Cu2ZnSnSxSe4-x (CZTSSe) have tunable bandgaps that are ideally suited for thin-film photovoltaics (PV) applications, high absorption coefficients due to direct bandgaps, and are extremely stable. However, these materials are conventionally manufactured using expensive and complicated vapor-phase reaction procedures or high-temperature, vacuum-based deposition methods. Our preliminary work has shown that chalcogen polymers can also be functionalized to directly coordinate with metal cations. This resulting hybrid organic-inorganic polymer can be printed onto a substrate and heated to initiate a chemical reaction that produces a metal-chalcogenide material such as CISSe. This new synthetic method provides a pathway towards making PV materials via a simple, completely solution-processed, low-temperature fabrication procedure. If successful, this technique would constitute the first viable means to produce low-bandgap chalcogenides without additional vapor-phase reactions or high-temperature sputtering depositions.

Chalcogen polymers for completely solution-processed inorganic photovoltaics

253rd National Meeting (2017)

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