Enhanced photoluminescence in a novel photobleached dithienylbenzo[c]thiophene oligomer derivative

Photoluminescence of a novel dithienylbenzo[c]thiophene oligomer has been s tudied in detail. Significant enhancement of photoluminescence has been obs erved in the material after photobleaching. The bleached oligomer was obser ved to be stable over time and had a photoluminescence peak significantly b lue shifted compared to the fresh material. UV-visible and FTIR spectroscop ic analyses indicated photooxidation to be the origin of bleaching. Photolu minescence efficiencies have been measured for both fresh and photobleached solutions. The PL quantum efficiencies have been determined to be 92% for the photobleached material, and 9% for the fresh solution. Spectral narrowi ng was observed in solid films of the bleached oligomer for excitation with 1 nJ, 200 fs pulses at 400 nm. (C) 2000 American Institute of Physics. [S0 021- 9606(00)70501-0].