Negative capacitance in doped bi-layer organic light-emitting devices

This paper reports that the doped bi-layer organic light-emitting devices are fabricated by doping the different regions of the light-emitting layer, the admittance and luminance spectra to characterize the capacitance and luminance of the device are measure. Negative capacitance (NC) appeared at low frequencies when the doped devices are biased with high voltages. The measured phase difference between AC voltage applied across the device and AC current flowing through the device show that the device is inductive when NC appears.