Thermally driven lattice-defect mitigation for high-performance quantum dot light-emitting diodes
Abstract:
Colloidal alloy quantum dots (QDs) with tunable emission wavelengths and tailorable structures are promising candidates for high-performance QDs light-emitting diodes (QLEDs). However, the uneven growth of alloy QDs leads to inhomogeneous structures and morphologies, resulting in lattice defect accumulation and suppressed photoluminescence quantum yields (PLQYs). Here, we present a versatile strategy for synthesizing high-quality alloy QDs with enhanced emission properties and reduced lattice defects. By rapidly injecting high-temperature anion precursors, we achieve uniform lattice growth and mitigate defects while preserving superior emission properties. The high-temperature (230°C) anion-injected synthetic alloy QDs (H-QDs) reach a PLQY up to 95%, significantly higher than the 82% obtained from room-temperature (25°C) anion-injected synthetic QDs (R-QDs). We fabricate green QLEDs based on CdSe@ZnS H-QDs, which demonstrate a maximum external quantum efficiency (EQE) of 22.4% and a lifetime of 506,000 h at 529 nm-outperforming R-QD-based devices (EQE: 11.3%, lifetime: 108,900 h). This method provides a new way for optimizing alloy QDs for advanced visible optoelectronic devices.
