期刊
ACS NANO
卷 15, 期 12, 页码 20332-20340出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.1c08631
关键词
quantum dot based light-emitting diodes (QD-LEDs); all-inorganic LEDs; NiO hole transport layer; interface dipole layer; ligand exchange
类别
资金
- National Research Foundation of Korea (NRF) - Ministry of Science, ICT and Future Planning [2021M3H4A3A01062964, 2020M3D1A2101319, 2020R1A2C2011478, 2021M3H4A1A01004332]
- Ministry of Trade, Industry & Energy (MOTIE, Korea) [20010737]
- Electronics and Telecommunications Research Institute (ETRI) - Korean government [20ZB1200]
- Samsung Display
- National Research Foundation of Korea [2021M3H4A3A01062964, 2020R1A2C2011478, 2021M3H4A1A01004332, 2020M3D1A2101319] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
By controlling the orientation of molecular dipoles on the surfaces of NiO HTL and QDs, bright and stable all-inorganic QD-LEDs were achieved with high external quantum efficiency and brightness, along with prolonged operational stability.
The state-of-the-art quantum dot (QD) based light-emitting diodes (QD-LEDs) reach near-unity internal quantum efficiency thanks to organic materials used for efficient hole transportation within the devices. However, toward high-current-density LEDs, such as augmented reality, virtual reality, and headup display, thermal vulnerability of organic components often results in device instability or breakdown. The adoption of a thermally robust inorganic hole transport layer (HTL), such as NiO, becomes a promising alternative, but the large energy offset between the NiO HTL and the QD emissive layer impedes the efficient operation of QD-LEDs. Here, we demonstrate bright and stable all-inorganic QD-LEDs by steering the orientation of molecular dipoles at the surfaces of both the NiO HTL and QDs. We show that the molecular dipoles not only induce the vacuum level shift that helps alleviate the energy offset between the NiO HTL and QDs but also passivate the surface trap states of the NiO HTL that act as nonradiative recombination centers. With the facilitated hole injection into QDs and suppressed electron leakage toward trap sites in the NiO HTL, we achieve allinorganic QD-LEDs with high external quantum efficiency (6.5% at peak) and brightness (peak luminance exceeding 77 000 cd/m(2)) along with prolonged operational stability. The approaches and results in the present study provide the design principles for high-performance all-inorganic QD-LEDs suited for next-generation light sources.
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