Photoinduced Aggregation of Polythiophenes

This letter describes thiophene-based materials that undergo photoinduced aggregation or precipitation upon irradiation with UV light. The only solubilizing side chains on these materials are photocleavable by connection through photolabile nitrobenzyl esters. While quaterthiophene oligomers yield diacids that remain soluble in dichloromethane at micromolar concentrations upon exposure to ultraviolet light, the polymeric analog shows both red-shifted absorbance and heavily quenched fluorescence, consistent with aggregation due to photochemical cleavage of solubilizing alkyl chains. Thin films of this polymer also resisted dissolution in organic solvent upon irradiation, suggesting applicability in the construction of multilayer solid-state devices.