Quantitative Determination of Charge Accumulation and Recombination in Operational Quantum Dots Light Emitting Diodes via Time-Resolved Electroluminescence Spectroscopy

In this work, we report the quantitative determination of charge accumulation and recombination in an operated QLED using time-resolved electroluminescence (TREL) spectroscopy. As a supplement technique, time-resolved current (TRC) measurement was introduced and simulated using equivalent circuit model with a series resistance, a parallel resistance, and a capacitance. By modeling the key processes in a typical TREL spectra, the stages of delay, rising, and decay can be correlated to the charge accumulations, charge injection and recombination, and charge release and recombination, respectively. In particular, the rising stage can be described using a modified Langevin recombination model. The electroluminescence recombination rate can be derived by fitting the rising stage curves in the TREL spectra, providing an intrinsic parameter of the emissive materials. In all, this work provides a methodology to quantitatively determine the charge accumulation and recombination of an operational QLED device.

Automated summary

In this study, the charge accumulation and recombination in an operational QLED were quantitatively determined using time-resolved electroluminescence (TREL) spectroscopy. Time-resolved current (TRC) measurement was introduced and simulated using an equivalent circuit model, including a series resistance, a parallel resistance, and a capacitance. The key processes in a typical TREL spectra were modeled, and the stages of delay, rising, and decay were correlated to charge accumulations, charge injection and recombination, and charge release and recombination, respectively. The electroluminescence recombination rate was derived by fitting the rising stage curves in the TREL spectra, providing an intrinsic parameter of the emissive materials.