Poly(2,5-diheptyl-1,4-phenylene-alt-2,5-thienylene): a new material for blue-light-emitting diodes

The electronic and chemical structures of a new polymer, poly(2,5-diheptyl-1,4-phenylene-alt-2,5-thienylene), have been studied experimentally by X-ray and ultraviolet photoelectron spectroscopies, and theoretically by quantum chemical calculations. Optical absorption and photoluminescence spectra were also obtained. In addition, single-layer light-emitting diodes, consisting of calcium electrodes deposited on polymer films which had been spin-coated on ITO glass, were fabricated in ultra-high vacuum, and the electroluminescence spectra as well as current-voltage curves were studied. The polymer was found to be highly fluorescent, emitting light of light-blue/green color. The light emitted from the diodes was turquoise in color and clearly visible in daylight.