Document Type

Journal Article


Department of Physics; Institute of Advanced Material




We report our effort to develop high performing all-solution-processable transparent inverted quantum-dot light-emitting diodes (QD-LEDs) by interposing an interface dipole between the ZnO electron-transporting layer (ETL) and the quantum dot light-emitting layer. It shows that the electrostatic interaction between the N+ groups in the polar conjugated polyelectrolyte molecules and the hydroxyl (OH) groups on the ZnO ETL surface creates the interface dipole. The presence of an optimal interface dipole benefits the efficient operation of QD-LEDs in two ways: (1) it effectively reduces the energy barrier at the ETL/QD emisive layer interface for efficient charge injection, and (2) it prevents the exciton quenching by suppression of ZnO surface defects. The combined effects resulted in a significant enhancement in the performance of the transparent inverted QD-LED, achieving an impressive high maximum luminance of 10011 cd/m2, which is 75% higher than that of a control device made with a pristine ZnO ETL (5721 cd/m2). QD-LEDs with an optimal interface dipole also possess a high luminous efficiency of 1.55 cd/A, which is 57% higher than that of a control QD-LED (0.99 cd/A).

Publication Date


Source Publication Title

Journal of Materials Chemistry C


Royal Society of Chemistry

Peer Reviewed



This is the accepted manuscript version of the article. Journal of Materials Chemistry C, 2018, DOI: 10.1039/C8TC00303C. This journal is © The Royal Society of Chemistry 2018.


This work was financially supported by the Research Grants Council of Hong Kong Special Administrative Region, China, General Research Fund (GRF/12303114, 12302817), Inter-institutional Collaborative Research Scheme (RC-ICRS/15-16/04) and Shenzhen Peacock Plan (KQTD20140630110339343).



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Available for download on Friday, March 01, 2019

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