Abstract
Ink-jet printing is a promising deposition technology, which is capable of large-area fabrication and mask-free patterning. For ink-jet-printed quantum dot (QD) light-emitting diodes (LEDs), the QDs are commonly dissolved in a mixture of solvent and thickener ink system. However, the hole transport layer could be eroded by this QD ink, leading to a rough surface morphology and resulting in the leakage of carriers and low device performance. This phenomenon was first and directly observed by using an atomic force microscope and a cross-sectional scanning electron microscope. We, therefore, redesigned the annealing process of the hole transport layer to achieve an optimized smooth surface with a reduced number of defects for ink-jet-printed QD LEDs (QLEDs). Optimized morphology brings back a maximum luminance of over 30,000 cd/m2 and an external quantum efficiency of 7.52% for the ink-jet-printed red QLEDs using CdSe QDs, which are comparable to those of the spin-coated device. Moreover, the operation lifetime of the ink-jet-printed device is also enhanced by the restored surface morphology. An enhanced T50 lifetime of the ink-jet-printed device at 1000 cd/m2 is improved from 26 to 127 h, which converted to a long T50 lifetime of 8013 h, when operated at 100 cd/m2.
Original language | English |
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Pages (from-to) | 3005-3014 |
Number of pages | 10 |
Journal | ACS Applied Electronic Materials |
Volume | 3 |
Issue number | 7 |
Early online date | 1 Jun 2021 |
DOIs | |
Publication status | Published - 27 Jul 2021 |
Bibliographical note
Funding Information:H.T. and S.J. have contributed equally to this work. We would like to acknowledge support from the Ministry of Science and Technology of China (nos. 2016YFB0401702 and 2017YFE0120400), the National Natural Science Foundation of China (nos. 61674074, 61875082, and 61405089), the Guangdong Province’s Key R&D Program: Micro-LED Display and Ultra-high Brightness Micro-display Technology (no. 2019B010925001); Environmentally Friendly Quantum Dots Luminescent Materials (no. 2019B010924001), the Guangdong Basic and Applied Basic Research Foundation (no. 2019A1515110437), the Guangdong University Key Laboratory for Advanced Quantum Dot Displays and Lighting (no. 2017KSYS007), the Shenzhen Innovation Project (no. JCYJ20180305180629908), the Guangdong Youth Innovative Talents Project (no. 2018KQNCX228), and the Shenzhen Peacock Team Project (no. KQTD2016030111203005). The authors would like to acknowledge the technical support from Dongsheng He and Yang Qiu in SUSTech CRF.
Publisher Copyright:
© 2021 ACS Applied Electronic Materials. All rights reserved.
Keywords
- annealing process
- erosion
- hole transporting layer
- ink-jet printing
- QLED
- stability
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrochemistry
- Materials Chemistry