Impact of Current on the Parallel Resistance and Junction Capacitance of Light-Emitting Diodes

The characteristics of the parallel resistance and junction capacitance (PRJC) of tricolor light-emitting diodes (LEDs) driven by periodic pulse currents were investigated, revealing that as the drive current increases, the parallel resistance decreases while the junction capacitance increases. The product of PRJC tends to decrease with increasing pulsewidth or amplitude of the driving current. The impedance spectra of LEDs were employed to extract the PRJC. When the voltage is close to the threshold, the parallel resistance dominates; however, the series resistance becomes dominant when the voltage exceeds the threshold. The impact of the parallel resistance on the I-V relationship cannot be ignored when LEDs operate under low-frequency pulse current and low current conditions.