Title: Spatial exciton allocation strategy with reduced energy loss for high-efficiency fluorescent/phosphorescent hybrid white organic light-emitting diodes

Abstract

Due to the poor operational lifetime of blue phosphorescent dopants and blue thermally activated delayed fluorescent (TADF) materials, hybrid white organic light-emitting diodes (WOLEDs) with conventional blue fluorescent emitters are still preferred for commercial applications in general lighting. However, the improvement in the overall efficiency of hybrid WOLEDs has been limited due to energy losses during the energy transfer process and exciton quenching after the spatial separation of the singlet and triplet excitons. Here we demonstrate the development of a Spatial Exciton Allocation Strategy (SEAS) to achieve close to 100% internal quantum efficiency (IQE) in blue-yellow complementary color hybrid WOLEDs. The employed blue fluorophore not only has a resonant triplet level with the yellow phosphor to reduce energy loss during energy transfer processes and triplet–triplet annihilation (TTA), but also has a resonant singlet level with the electron transport layer to extend singlet exciton distribution and enhance both singlet and triplet exciton utilization. Thus, the resulting hybrid WOLEDs exhibited 104 lm W^-1 efficacy at 100 cd m^-2 and 74 lm W^-1 at 1000 cd m^-2 with CIE coordinates of (0.42, 0.44) which is warm white and suitable for indoor lighting.

Authors:

Zhao, Fangchao  ^[1];

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Wei, Ying ^[2]; Xu, Hui ^[2]; Chen, Dustin ^[3]; Ahamad, Tansir ^[4]; Alshehri, Saad ^[5]; Pei, Qibing ^[3]; Ma, Dongge ^[6]

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+ Show Author Affiliations

1. South China Univ. of Technology (SCUT), Guangzhou (China). Inst. of Polymer Optoelectronic Materials and Devices, State Key Lab. of Luminescent Materials and Devices; Univ. of California, Los Angeles, CA (United States). Henry Samueli School of Engineering and Applied Science and Dept. of Materials Science and Engineering
2. Heilongjiang Univ., Harbin (China). Ministry of Education and State Key Lab. of Functional Inorganic Material Chemistry
3. Univ. of California, Los Angeles, CA (United States). Henry Samueli School of Engineering and Applied Science and Dept. of Materials Science and Engineering
4. King Saud Univ., Riyadh (Saudi Arabia). Dept. of Chemistry
5. King Saud Univ., Riyadh (Saudi Arabia). Dept. of Chemistry; Alfaisal Univ., Riyadh (Saudi Arabia). College of Science and General Studies and Dept. of Chemistry
6. South China Univ. of Technology (SCUT), Guangzhou (China). Inst. of Polymer Optoelectronic Materials and Devices, State Key Lab. of Luminescent Materials and Devices; King Saud Univ., Riyadh (Saudi Arabia). Dept. of Chemistry

Publication Date:

2017-05-17

Research Org.:

Univ. of California, Los Angeles, CA (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:

1429117

Grant/Contract Number:  

EE0006674

Resource Type:

Accepted Manuscript

Journal Name:

Materials Horizons

Additional Journal Information:

Journal Volume: 4; Journal Issue: 4; Journal ID: ISSN 2051-6347

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

42 ENGINEERING; 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Lighting, OLED