RADIATION-INDUCED PHOTOLUMINESCENCE QUENCHING OF PHENYLENE VINYLENE OLIGOMER THIN-FILMS

We have studied the radiation-induced photoluminescence (PL) quenching and the associated electronic structure modification of a light-emitt ing conjugated oligomer, namely, 1,4-bis[4-(3,5-di-tert-butylstyryl)st yryl]benzene (4PV), in the absence of oxygen. We found that a shea per iod of exposure to the radiation sources used in UV or x-ray photoelec tron spectroscopies (UPS or XPS) resulted in total PL quenching in 4PV . Although there was no detectable change in the XPS C 1s core-level s pectra UPS valence spectra indicated the disappearance of the vinylene peak upon exposure to UV radiation. This suggests the destruction of the vinylene groups, and the possible creation of radical species, whi ch may serve as PL quenching sites. We also found that the modificatio n in the electronic structure by Ca deposition masks that by radiation , although both quenches the PL effectively.