Tandem Quantum Dot Light-Emitting Diodes: Interlayer Engineering and Performance Optimization

Abstract

Tandem quantum dot light-emitting diodes (T-QLEDs) have attracted considerable attention in next-generation display and solid-state lighting technologies due to their outstanding external quantum efficiency (EQE), high brightness, and extended operational lifetime. A critical component in T-QLEDs is the intermediate connecting layer (ICL), which facilitates efficient charge generation, transport, and injection between stacked emissive units. The design and optimization of ICL are essential to achieving charge balance, minimizing non-radiative losses, and enhancing overall device stability. This review provides a comprehensive overview of the fundamental architecture and working principles of T-QLEDs, with a particular focus on the fabrication and engineering of ICL. Two primary fabrication approaches—thermal evaporation and solution processing—are discussed in detail, along with optimization strategies tailored to both conventional and inverted device configurations. Recent advances in novel ICL materials and structural innovations for performance enhancement are also highlighted. Finally, this review addresses practical considerations for commercialization, including process scalability, material costs, compatibility with printing and roll-to-roll manufacturing, and key technical and economic bottlenecks that must be overcome for the widespread adoption of T-QLEDs.