Temperature dependence of the electroluminescence and the photoluminescence of a silyl-disubstituted poly(p-phenylenevinylene) derivative

Abstract

We have studied the temperature dependences of the current-voltage (I - V) characteristics, the electroluminescence (EL), and the photoluminescence (PL) of light-emitting diodes fabricated with poly(2, 5-bis(dimethyloctylsilyl)-1,4-phenylenevinylene) (BDMOS-PPV). The ITO/BDMOSPPV/Al devices show green light emission under both forward and reverse biases. The I-V characteristics under both biases fit the Fowler-Nordheim tunneling formula kt high fields, and the current and the EL intensity under a constant bias are independent of temperature below about 270 K, indicating that the tunneling of charge carriers is an important injection process. The EL spectra under both biases are very similar to the PL spectra and are narrower compared than the optical absorption spectrum. These results and a red-shift of the transient PL spectra with time imply that excitons migrate towards longer conjugated segments prior to recombination.