Positive Aging-Free Quantum Dot Light-Emitting Diodes Enabled by Single-Source Chloride-Doped ZnMgO Electron
Jaeyeop Lee1, Yeyun Bae1, Kyoungeun Lee1
1Department of Electrical Engineering, Pusan National University, Busan, Republic of Korea.
Abstract:
Colloidal quantum dot light-emitting diodes (QD-LEDs) offer narrowband, color-pure emission, solution processability, and wavelength tunability for next-generation displays. However, commercialization is hindered by positive aging-a storage-driven drift in which device external quantum efficiency (EQE) increases for several days before peaking, reflecting slow interfacial trap passivation in oxide electron-transport layers (ETLs). This drift delays qualification, complicates calibration, and degrades device-to-device uniformity because the as-fabricated performance does not represent the final state. Here, we suppress positive aging by pre-stabilizing ZnMgO ETLs via single-source chloride doping (MgCl2), which mitigates oxygen vacancy (OV)-related defect signatures. Time-dependent X-ray photoelectron spectroscopy, single-carrier device measurements, and steady-state/time-resolved QD photoluminescence show that undoped ZnMgO undergoes gradual defect passivation during storage, whereas Cl-doped ZnMgO remains nearly time-invariant. As a result, devices with Cl-doped ZnMgO reach peak EQE at day 0 and maintain it during storage, while devices with undoped ZnMgO require several days to reach peak efficiency. In addition, as-fabricated QD-LEDs employing Cl-doped ZnMgO exhibit ≈1.8× higher peak EQE and ≈1.3× longer operational lifetime than undoped controls, with negligible positive aging signatures. This intrinsic ETL stabilization enables day-0 calibration, improves uniformity and yield, and removes the need for storage-driven conditioning-identifying single-source chloride doping as a practical route to robust ZnMgO ETLs for display applications.
