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Improving Performance of Inverted Blue Quantum‐Dot Light‐Emitting Diodes by Adopting Organic/Inorganic Double Electron Transport Layers
Author(s) -
Park Myeongjin,
Song Jiyun,
Jung Heeyoung,
An Myungchan,
Lim Jaehoon,
Lee Changhee,
Roh Jeongkyun,
Lee Donggu
Publication year - 2020
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201900737
Subject(s) - light emitting diode , optoelectronics , quantum dot , materials science , diode , oxide , electron , leakage (economics) , quantum efficiency , metal , nanoparticle , nanotechnology , physics , quantum mechanics , economics , metallurgy , macroeconomics
Colloidal quantum dots (QDs) have many advantages in optoelectronic applications such as light‐emitting diodes (LEDs), solar cells, and photocatalysts because of their superb optical and electrical properties that can be tuned by changing the shapes and sizes of the QDs. The efficiency of QD‐LEDs is significantly improved as inorganic metal oxide nanoparticles (NPs) are adopted for electron transport layers (ETLs) because of the high electron mobility of the NPs. However, there are two significant drawbacks of the ETLs with metal oxide NPs that hinder device performance and stability: low compactness of the metal oxide NP films that generate a massive leakage current pathway and charge imbalance caused by spontaneous electron injection from metal oxide ETLs into the QDs. To address these drawbacks, an organic/inorganic double ETL is introduced consisting of 1,3,5‐tris(2‐ N ‐phenylbenzimidazolyl)benzene (TPBi) and zinc oxide (ZnO) NPs. By depositing TPBi on the ZnO NP ETL, the pinholes and cracks present in the ZnO NP layer are filled successfully, preventing the leakage current pathway. Furthermore, TPBi also works as a “charge balancer” by suppressing spontaneous electron injection from the ETL into the QDs. As a result, twice the external quantum efficiency and three times the lifetime are obtained with the blue QD‐LEDs.