Issue 44, 2019

Highly efficient deep-blue light-emitting copolymers containing phenoxazine: enhanced device efficiency and lifetime by blending a hole transport molecule

Abstract

A series of deep-blue light-emitting copolymers with an emission peak at 455 nm and narrow full width at half-maximum (FWHM) of about 40 nm were synthesized by incorporating a small amount of 10-(4-hexylphenyl)-10H-phenoxazine (PO) unit into the backbone of poly(9,9-dioctylfluorene). All the copolymers exhibit good thermal stability, high photoluminescent quantum yield and appropriate electrochemical energy levels. The copolymer PF-TD2PO1 which contains 1 mol% PO unit shows a maximum luminous efficiency (LEmax) of 3.07 cd A−1 and 5.18 cd A−1 based on single-layer and double-layer devices, respectively, with deep-blue Commission Internationale de L’E’clairage (CIE) coordinates of (0.15, 0.11). To improve the hole transport of the emissive layer, a hole transport molecule N-([1,1′-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazo-yl)-phenyl)-9H-fluorene-2-amine (BCFN) was blended into PF-TD2PO1. As a result, the best electroluminescence performance with a low turn-on voltage of 3.0 V, a superior LEmax of 6.20 cd A−1 (corresponding to a maximum external quantum efficiency of 6.22%), an unprecedented luminance of 44 685 cd m−2 and deep-blue CIE coordinates of (0.15, 0.11) were obtained from the blended PF-TD2PO1:BCFN light emitting device. It is particularly important that PF-TD2PO1:BCFN based devices exhibit very slow efficiency roll-off and a more than 14 times enhanced lifetime compared with the devices without BCFN. The results indicate the great potential of this class of copolymers for application in solution processed deep-blue light-emitting diodes with high efficiency and long lifetime.

Graphical abstract: Highly efficient deep-blue light-emitting copolymers containing phenoxazine: enhanced device efficiency and lifetime by blending a hole transport molecule

Supplementary files

Article information

Article type
Paper
Submitted
27 Aug. 2019
Accepted
04 Okt. 2019
First published
07 Okt. 2019

J. Mater. Chem. C, 2019,7, 13859-13866

Highly efficient deep-blue light-emitting copolymers containing phenoxazine: enhanced device efficiency and lifetime by blending a hole transport molecule

J. He, Z. Huang, Z. Huang, S. Liao, F. Peng, Z. Zhong, T. Guo, L. Ying and Y. Cao, J. Mater. Chem. C, 2019, 7, 13859 DOI: 10.1039/C9TC04721B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements