Lee Hyo Geun, Kwon Yong Woo, Jung Woon Ho, Lee Hyeonjun, Kim Min Seok, Kim Hyun-Mi, Kim Hyeongkeun, Kim Hae Jin, Lee Doh C, Lim Jaehoon, Cho Seong-Yong
Department of Photonics and Nanoelectronics, and BK21 FOUR ERICA-ACE Center, Hanyang University, Ansan 15588, Korea.
Korea Electronics Technology Institute, Seongnam 13509, Korea.
ACS Appl Mater Interfaces. 2025 Jan 15;17(2):3597-3607. doi: 10.1021/acsami.4c17722. Epub 2025 Jan 6.
Colloidal quantum-dot light-emitting diodes (QD-LEDs) have been significantly improved in terms of device performance and lifetime by employing zinc oxide (ZnO) as an electron transport layer (ETL). Although atomic layer deposition (ALD) allows fabrication of uniform, high-quality ZnO films with minimal defects, the high conductivity of ZnO has hindered its straightforward application as an ETL in QD-LEDs. Herein, we propose fabrication of Al-doped ZnMgO (Al:ZnMgO) ETLs for QD-LEDs through a supercycle ALD, with alternating depositions of various metal oxides. The supercycle ALD allows for extensive control of compositions, which is not possible in typical hydrolysis-based approaches. ZnMgO alloys produced by ALD adjust the band gap to match the QDs and suppress the electron injection. However, Mg compositions of >10% lead to a reduction in electron conductivity, limiting the charge balance in the QDs. The Al doping provides Al ions, oxygen vacancies, and zinc interstitials to compensate for the reduced conductivity of ZnMgO. Composition tuning based on the supercycle ALD enables to realize the ETLs offering optimal electron injection capability without compromising the electrical conductivity. QD-LEDs with the Al:ZnMgO ETLs exhibit a peak external quantum efficiency of 15.7% and peak luminance of 167,000 cd m, on par with typical devices using ZnMgO nanocrystal-based ETLs.
通过采用氧化锌（ZnO）作为电子传输层（ETL），胶体量子点发光二极管（QD-LED）在器件性能和寿命方面有了显著提高。尽管原子层沉积（ALD）能够制造出均匀、高质量且缺陷最少的ZnO薄膜，但ZnO的高电导率阻碍了其在QD-LED中直接用作ETL。在此，我们提出通过超循环ALD制备用于QD-LED的Al掺杂ZnMgO（Al:ZnMgO）ETL，其中各种金属氧化物交替沉积。超循环ALD允许对成分进行广泛控制，这在典型的基于水解的方法中是不可能的。通过ALD制备的ZnMgO合金可调节带隙以匹配量子点并抑制电子注入。然而，Mg含量大于10%会导致电子电导率降低，限制了量子点中的电荷平衡。Al掺杂提供了Al离子、氧空位和锌间隙原子来补偿ZnMgO降低的电导率。基于超循环ALD的成分调整能够实现具有最佳电子注入能力且不损害电导率的ETL。具有Al:ZnMgO ETL的QD-LED表现出15.7%的峰值外量子效率和167000 cd m的峰值亮度，与使用基于ZnMgO纳米晶体的ETL的典型器件相当。
