High‐Efficiency and Stable ZnSeTe‐Based Blue QLEDs Enabled by Freeze‐Dried SnO₂ Nanoparticle Interlayers

Abstract Quantum dot light‐emitting diodes (QLEDs) have emerged as a promising next‐generation technology for display and lighting applications due to their outstanding color performance. However, despite considerable progress, blue QLEDs, especially those based on nonheavy metal materials, continue to face significant challenges in efficiency and stability, falling behind their red and green counterparts. Herein, a new strategy is presented to enhance the performance of ZnSeTe‐based blue QLEDs by introducing SnO 2 nanoparticles (NPs) prepared via freeze‐drying technology as a conductive interlayer between the quantum dot (QD) layer and ZnO electron transport layer (ETL). This approach improves the dispersion of SnO 2 NPs, reduces film surface roughness, and effectively suppresses device leakage currents. Furthermore, the freeze‐drying process minimizes oxygen vacancies in SnO 2 and reduces exciton quenching at the QD/ETL interface. As a result, the ZnSeTe‐based blue QLEDs utilizing the freeze‐dried SnO 2 NP interlayer achieve a maximum external quantum efficiency (EQE) of 20.8%, a peak brightness of 6017 cd m −2 , and a T 50 operational lifetime of 130.7 h at a brightness of 100 cd m −2 . These findings represent a significant improvement in the efficiency and stability of environmentally friendly blue QLEDs and provide valuable insights for advancing QLED technology.