Analysis of Emission Zone Profile in an Organic–Quantum Dots Hybrid Device

We utilize an inverted quantum dot light-emitting diode (QLED) as the experimental model in this work. By visualizing the emission zone profiles of QLEDs, we discuss the balance of n- and p-type currents and the resultant recombination site in the EML of the QLEDs. The findings demonstrate that the emission zone profiling is a competent method which helps us understand the efficiency loss mechanism in a QLED and hence expand possibilities for further improvement of the future device performance.

By utilizing a unique analytical method, the emission zone profiles of an organic–QD hybrid system were first time visualized. The emission zone of our inverted QLED was forced to be concentrated due to a domination of the n-type current in the EML. The imbalance of n/p current ratio was improved by controlling the conductivity of the ETL, drastically improving the device EQE and suppressing the roll-off. The insights obtained from the emission zone analysis are valuable for understanding the device physics in QLEDs. We expect that the method to combine the emission zone analysis and the electrical device tuning will accelerate development of high-performance and long-lived organic–QD hybrid devices.