Department of Physics, National Taiwan University, Taipei 106, Taiwan.
Department of Materials Science and Engineering, National United University, Miaoli 360, Taiwan.
ACS Appl Mater Interfaces. 2023 May 31;15(21):25744-25751. doi: 10.1021/acsami.3c01566. Epub 2023 May 18.
Quantum dot light-emitting diodes (QLEDs) are an emerging class of optoelectronic devices with a wide range of applications. However, there still exist several drawbacks preventing their applications, including long-term stability, electron leakage, and large power consumption. To circumvent the difficulties, QLEDs based on a self-assembled hole transport layer (HTL) with reduced device complexity are proposed and demonstrated. The self-assembled HTL is prepared from poly[3-(6-carboxyhexyl)thiophene-2,5-diyl] (P3HT-COOH) solution in ,-dimethylformamide (DMF) forming a well-ordered monolayer on an indium-tin-oxide (ITO) anode. The P3HT-COOH monolayer has a smaller HOMO band offset and a sufficiently large electron barrier with respect to the CdSe/ZnS quantum dot (QD) emission layer, and thus it is beneficial for hole injection into and electron leakage blocking from the QD layer. Interestingly, the QLEDs exhibit an excellent conversion efficiency (97%) in turning the injected electron-hole pairs into light emission. The performance of the resulting QLEDs possesses a low turn-on voltage of +1.2 V and a maximum external quantum efficiency of 25.19%, enabling low power consumption with high efficiency. Additionally, those QLEDs also exhibit excellent long-term stability without encapsulation with over 90% luminous intensity after 200 days and superior durability with over 70% luminous intensity after 2 h operation under the luminance of 1000 cd m. The outstanding device features of our proposed QLEDs, including low turn-on voltage, high efficiency, and long-term stability, can advance the development of QLEDs toward facile large-area mass production and cost-effectiveness.
量子点发光二极管 (QLED) 是一类新兴的光电设备，具有广泛的应用。然而，其应用仍存在一些缺点，包括长期稳定性、电子泄漏和高功耗。为了克服这些困难，提出并展示了基于自组装空穴传输层 (HTL) 的 QLED，可降低器件复杂性。自组装 HTL 由聚[3-(6-羧基己基)噻吩-2,5-二基] (P3HT-COOH) 在二甲基甲酰胺 (DMF) 溶液中制备，在铟锡氧化物 (ITO) 阳极上形成有序的单层。P3HT-COOH 单层具有较小的 HOMO 能带偏移和与 CdSe/ZnS 量子点 (QD) 发射层足够大的电子势垒，因此有利于空穴注入和电子从 QD 层泄漏。有趣的是，QLED 将注入的电子-空穴对转换为光发射时表现出优异的转换效率 (97%)。所得 QLED 的性能具有低开启电压 (+1.2 V) 和最大外量子效率 25.19%，可实现高效率、低功耗。此外，那些 QLED 即使不封装也具有出色的长期稳定性，在 200 天后仍保持超过 90%的亮度，在 1000 cd m 的亮度下运行 2 小时后仍保持超过 70%的亮度，具有卓越的耐用性。我们提出的 QLED 的出色器件特性，包括低开启电压、高效率和长期稳定性，可推动 QLED 朝着易于大规模生产和具有成本效益的方向发展。
