Charge Generation Junction for Efficient Hole Injection in InP-Based Quantum Dot Light-Emitting Diodes

Abstract

To achieve high-performance colloidal quantum dot light-emitting diodes (QD-LEDs) suitable for commercialization, maintaining charge neutrality within the QD emissive layer is essential to suppress nonradiative Auger recombination. However, in conventional QD-LEDs, the electron injection rate often exceeds that of the holes, leading to charge imbalance and Auger recombination. This study aims to address the aforementioned issue by introducing a charge-generation p-n junction (CGJ) to facilitate efficient hole injection in InP-based QD-LEDs. The incorporation of the CGJ enables work-function-independent charge carrier injection, significantly enhancing the hole injection rate. Single-carrier device measurements and capacitance-voltage analysis confirm that the CGJ improves the hole injection efficiency and significantly increases the hole current. Consequently, devices incorporating the CGJ exhibit a two-fold improvement in both maximum luminance (from 11,080 to 22,692 cd m-2) and external quantum efficiency (from 5.33 to 11.01%) compared to devices without the CGJ. Furthermore, the CGJ-based QD-LEDs demonstrate an order-of-magnitude enhancement in the operational lifetime, highlighting that a robust charge balance is achieved. These findings demonstrate the effectiveness of the CGJ as a powerful tool for improving the performance and stability of InP-based QD-LEDs, thereby advancing their potential for widespread adoption in next-generation optoelectronic devices.