Solar cell efficiency may be improved via the conversion of low energy photons to high energy photons through the process of triplet-triplet annihilation (TTA). TTA is a spin-allowed process where two triplets collide with (or 'annihilate') each other to form one molecule in its first excited state, and the other in its ground state. This allows photons smaller than the bandgap of solar cells to be captured. However, the current high upconversion quantum yields in TTA-based upconversion are measured in solution. Solid state systems are inefficient due to molecular aggregation or phase separation at low annihilator concentrations. In this research, we present an original approach for the use of a 9, 10 diphenylanthracene (DPA) analog, as the annihilator, covalently bonded to an acrylate polymer. This allows for controlled loadings exceeding 14 wt% without aggregation or phase separation. CdSe nanocrystals functionalized with 9-anthracenecarboxlyic acid ligands server as the sensitizer. When excited with visible (532 nm) light, upconverted emission from DPA (432 nm) was observed. This presents a significant step forward in the formation of a thin film for efficient solid state upconversion for use in third-generation solar cells.

Polymer-nanoparticle composite thin-films for photon upconversion

251st National Meeting (2016)

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