Positive Aging-Free Quantum Dot Light-Emitting Diodes Enabled by Single-Source Chloride-Doped ZnMgO Electron...

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Colloidal quantum dot light-emitting diodes (QD-LEDs) promise advanced display technologies due to their pure colors and tunable wavelengths.
• Commercialization is impeded by positive aging, a phenomenon where device efficiency (EQE) drifts post-fabrication due to slow trap passivation in electron-transport layers (ETLs).

Purpose of the Study:

• To mitigate positive aging in QD-LEDs by stabilizing the ZnMgO ETL.
• To investigate the impact of chloride doping on the defect dynamics and stability of ZnMgO ETLs.

Main Methods:

• Single-source chloride doping (MgCl2) of ZnMgO ETLs.
• Time-dependent X-ray photoelectron spectroscopy (XPS) to analyze defect signatures.
• Single-carrier device measurements and photoluminescence (PL) studies to assess device performance and stability.

Main Results:

• Chloride-doped ZnMgO ETLs demonstrated time-invariant properties, unlike undoped ZnMgO which showed gradual defect passivation during storage.
• QD-LEDs with Cl-doped ZnMgO achieved peak EQE on day 0 with no aging drift, unlike controls requiring several days.
• Cl-doped devices exhibited 1.8x higher peak EQE and 1.3x longer operational lifetime compared to undoped devices.

Conclusions:

• Single-source chloride doping effectively stabilizes ZnMgO ETLs, suppressing positive aging in QD-LEDs.
• This stabilization allows for immediate device calibration, improves uniformity, and enhances overall device performance and reliability.
• Chloride-doped ZnMgO presents a viable pathway for robust ETLs in next-generation display technologies.