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Highly Stable and Scalable Blue QD‐LED via an Evaporated TiO 2 Thin Film as an Electron Transport Layer
Author(s) -
Bang Sang Yun,
Fan XiangBing,
Jung SungMin,
Yang Jiajie,
Shin DongWook,
Suh YoHan,
Lee Tae Hoon,
Lee Sanghyo,
Choi Hyung Woo,
Occhipinti Luigi G.,
Han Soo Deok,
Kim Jong Min
Publication year - 2020
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.202001172
Subject(s) - materials science , optoelectronics , thin film , light emitting diode , electroluminescence , photoluminescence , layer (electronics) , full width at half maximum , diode , quantum efficiency , nanotechnology
Quantum dot‐based light‐emitting diodes (QD‐LEDs) have excellent optical properties; however, their limitations of stability, reproducibility, and scalability due to the solution process are the major drawback. Herein, blue QD‐LEDs fabricated with the conventional vacuum process using an e‐beam‐evaporated TiO 2 thin film as an electron transport layer (ETL) are demonstrated. CdZnS/ZnS‐based blue LEDs with a TiO 2 thin film are fabricated under ambient conditions. They exhibit maximum external quantum efficiencies of 3.53% and a peak luminance of 2847 cd m −2 . These values are retained, which minimizes performance degradation under high potential bias. In addition, the optimized evaporated TiO 2 thin film has a negligible red shift (0.5 nm) of the peak wavelength between the photoluminescence spectrum and electroluminescence spectrum with stable full‐width at half‐maximum changing by less than 2 nm at high voltage. Finally, a blue QD‐LED is fabricated on a scalable emission area of 2 × 2 in. with a patterned cathode accompanied by an evaporated TiO 2 thin film, which allows to perform conventional photolithography. A highly stable and reproducible vaporized inorganic thin film as the ETL supports the multilayer architecture to minimize the process damage.