The electronic structures and the optical properties of two anthracene derivatives, DBMA and DAA, are investigated by both experimental tech- niques and quantum chemical calculations. The cy- clic voltammetry and differential pulse polarograph measurement revealed that the introduction of ben- zol-imidazol and pyrrolo-pyridine group on the an- thracene block can affect the electrochemical be- havior of DBMA and DAA. Both UV/visible absorption and emission spectra of DBMA and DAA are red-shifted in contrast to the unsubstituted anthra- cene, so that the anthracene derivatives emit at blue-green region and the luminescence yields are remarkably elevated (over 90%). The B3LYP/6-31G theoretical calculations explored that the electronic structures of the anthracene derivatives are per- turbed by the side substitutes on the anthracene block, and the slight variation of the electronic struc- tures results in the enhanced electron accepting abil- ity and the decrease of the HOMO-LUMO energy gap, which is the origin of the emission to be shifted to blue-green region. The non-planar geometry struc- tures of DBMA and DAA are responsible for the ex- cellent luminescence yields.
The spectral and polarity dependence of the quantum yield of charge carrier photo-generation was stud-ied by steady-state photocurrent measurement in a single layer PhPPV film, double layer film of PhPPV and R6G and doped film of PhPPV with R6G. The intrinsic and extrinsic charge carrier photogeneration was observed. The result indicates that the quantum efficiency of the double layer device is higher than that of single layer device under reverse bias, but it is opposite under forward bias. The yield of charge carrier photogeneration of the doped film is higher than that of the other two films at both forward and reverse bias because of the increased interface area between the electron donor and acceptor.
