Electroluminescence in amorphous pyrazoline films under DC fields.

We have investigated the electroluminescence, EL, behavior in amorphous films of a pyrazoline derivative under DC fields. The current density vs. voltage characteristics indicated a space charge limited current behavior with traps distributed exponentially within the forbidden energy gap. EL was detected in the current range of double carrier injection which occurred after all traps in the sample were filled up. Spectral studies showed that the light emission zone was localized around the cathode side of the pyrazoline film. The brightness, measured as a function of current density, indicated the EL in the lower current density range to be dominated by delayed luminescence.