Positive impact of chromophore flexibility on the efficiency of red thermally activated delayed fluorescence materials
- 1 February 2021
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Mater. Horiz.
- Vol. 8 (4), 1297-1303
- https://doi.org/10.1039/d1mh00028d
Abstract
Rigid electron donors (D) and acceptors (A) have been widely used in recent years for the construction of D–A type thermally activated delayed fluorescence (TADF) materials. However, the chromophore robustness does not always make a positive contribution to the high efficiency of TADF materials. Here, the comparison study of two D–A type red TADF compounds (PT-TPA and PT-Az) demonstrated, for the first time, the positive impact of chromophore flexibility on the efficiency of TADF materials. In PT-Az, the rotation of terminal phenyl groups is restrained by an ethylene linker, leading to its inferior photoluminescence quantum yield (PLQY). In contrast, PT-TPA with free rotation of the phenyl groups showed a low reorganization energy and a large transition dipole moment for the S1 → S0 transition, which resulted in a high fluorescence radiative decay rate. As a result, the optimized devices based on PT-TPA gave a maximum external quantum efficiency (EQE) of 29.7% (632 nm) when doped in a single host and an EQE of 28.8% (648 nm) in an exciplex host. This study provided an insight into the impact of chromophore flexibility on the photophysical properties and device efficiency of TADF materials, and these results may provide valuable guidance for the molecular design of efficient emitters.Keywords
Funding Information
- National Key Research and Development Program of China (2016YFB0400703)
- National Natural Science Foundation of China (21871199, 21933002)
- Collaborative Innovation Center of Suzhou Nano Science and Technology
- Priority Academic Program Development of Jiangsu Higher Education Institutions
- State Administration of Foreign Experts Affairs
This publication has 48 references indexed in Scilit:
- Highly Efficient Near‐Infrared Delayed Fluorescence Organic Light Emitting Diodes Using a Phenanthrene‐Based Charge‐Transfer CompoundAngewandte Chemie, 2015
- Highly efficient red OLEDs using DCJTB as the dopant and delayed fluorescent exciplex as the hostScientific Reports, 2015
- Multicolored‐Fluorescence Switching of ICT‐Type Organic Solids with Clear Color Difference: Mechanically Controlled Excited StateChemistry – A European Journal, 2014
- Thermally Activated Delayed Fluorescence Materials Towards the Breakthrough of OrganoelectronicsAdvanced Materials, 2014
- Efficient and Stable White Organic Light‐Emitting Diodes Employing a Single EmitterAdvanced Materials, 2014
- Multiwfn: A multifunctional wavefunction analyzerJournal of Computational Chemistry, 2011
- Performance improvement of dye-sensitizing solar cell by semi-rigid triarylamine-based donorsDyes and Pigments, 2011
- Highly Efficient Green and Blue‐Green Phosphorescent OLEDs Based on Iridium Complexes with the Tetraphenylimidodiphosphinate LigandAdvanced Materials, 2011
- Electroluminescence from triplet metal—ligand charge-transfer excited state of transition metal complexesSynthetic Metals, 1998
- Organic electroluminescent diodesApplied Physics Letters, 1987