Upconversion via triplet-triplet annihilation (TTA) is an effective method of converting low energy photons into higher energy photons. TTA is a bipartite process where two triplets collide to form one molecule in the first excited state and the other in the ground state. While high quantum yields have been observed in solutions it is important to produce thin films that will enhance solar cells efficiencies. Our work utilizes colloidal cadmium selenide nanocrystals as sensitizers with diphenylanthracene (DPA) analogs as pendant groups bound to an acrylate polymer. The use of nanocrystals as sensitizers provides a highly tunable bandgap which provides advantages over molecular sensitizers. Additionally, the polymer design prevents molecular aggregation and allows for higher annihilator concentrations. Excitation with visible (488 nm) light produced upconverted emission from the DPA (432 nm).The film potentially could be mounted behind a single junction photovoltaic cell to harvest unused photons. This solid state design presents a promising route for increasing solar cell efficiencies.

Thin film upconversion sensitized by zinc-blende CdSe nanocrystals

253rd National Meeting (2017)

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