Dependence of Transient Current and Capacitance of Organic Light-Emitting Diodes on Pulsed Bias Conditions

We have employed a simple circuit combining pulse generator and capacitance meter to investigate transient current (TC) and capacitance of organic light-emitting diodes (OLEDs). The dependence of TC on OLEDs structure with the change in thickness of hole transport layer (HTL), and pulse regimes with the change in voltage and frequency have been studied. Results revealed that two different evolution pattern of TC at low and high electric fields, and the change in HTL affected TC much greatly at high electric fields. The capacitance-voltage curve with different frequency was observed and showed trapped- charge state and interfacial charge transport process near the electrode.