Organic π-conjugated trimers as fluorescent molecules for colorful electroluminescence

• Published in: New journal of chemistry Vol. 48; no. 44; pp. 18987 - 18994
• Main Authors: Deng, Yanhong, Wang, Yifei, Chen, Zhesheng, Xu, Bo, Wang, Jinjiang, Cloutet, Eric, Yuan, Xiaojiao, Xiang, Hengyang
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 11.11.2024
• Subjects: Brightness; Carbazoles; Chemical synthesis; Color; Electroluminescence; Emitters; Fluorescence; Lighting; Low molecular weights; Molecular structure; Organic light emitting diodes; Quantum efficiency; Quinoxalines; Spectral emittance; Trimers
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/D4NJ03241A

Organic fluorescent emitters based on π-conjugated small molecules show tremendous potential for display, lighting, and bio-imaging applications. However, these emitters face challenges of aggregation-caused quenching and limitations of color range caused by synthetic complexity and undesirable efficiency and quantum yield. In this work, by using quinoxaline/2,1,3-benzothiadiazole as central electron acceptors, and employing carbazole/thiophene/3,4-ethylenedioxythiophene as terminal electron donors, a series of π-conjugated fluorescent trimers with very low molecular weights ( M w = 294–466) were designed and synthesized. Modulating the molecular structure through the incorporation of distinct electron donor and acceptor moieties, broad spectral tuning from blue to red in the π-conjugated trimers was achieved. These conjugated trimers when applied as emitting layers in electroluminescent devices, particularly organic light-emitting diodes (OLEDs), exhibit high brightness and color-tunable electroluminescence (EL) peaks from 528 to 605 nm. The meticulously optimized device demonstrates excellent performance with a high brightness of 3857.19 cd m −2 , and an external quantum efficiency (EQE) of 2.29%. These π-conjugated trimers, synthesized by a simple synthesis process, present a viable avenue for low-cost luminescence lighting and display applications.