Boron-based TADF emitters with improved OLED device efficiency roll-off and long lifetime
| Autor: | Kenneth L. Kearns, Tomas D. Paine, David S. Laitar, Timothy S. De Vries, Jeong-Hwan Jeon, Sukrit Mukhopadhyay, Thomas P. Clark, Aaron A. Rachford, Timothy J. Gallagher, Hong-Yeop Na, Bruce M. Bell, Yuming Lai, Mcintire Travis E |
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| Rok vydání: | 2017 |
| Předmět: |
Photoluminescence
Materials science business.industry Process Chemistry and Technology General Chemical Engineering chemistry.chemical_element 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Acceptor 0104 chemical sciences Delocalized electron chemistry Excited state OLED Optoelectronics Density functional theory Singlet state 0210 nano-technology business Boron |
| Zdroj: | Dyes and Pigments. 141:83-92 |
| ISSN: | 0143-7208 |
| DOI: | 10.1016/j.dyepig.2017.01.055 |
| Popis: | A class of four-coordinate boron complexes is reported that contain both electron-rich and electron-poor functional groups. Judicious selection of donor and acceptor moieties with the use of a boron atom as a separating node yields charge transfer complexes capable of thermally activated delayed fluorescence (TADF). Complexes were prepared by a modular method providing access to a wide range of emission colors. The singlet (S1) and triplet (T1) energies are independently tuned to achieve a small S1-T1 gap. Raising and lowering of S1 and T1 states can be predicted using cyclic voltammetry, NTO analysis, and spin density distribution as determined using Density Functional Theory; separation of the hole and electron wavefunction for S1 excitation and delocalization of spin density distribution in the T1 state can help in achieving negligible S1-T1 gap. Although photoluminescent quantum yields of the boron complexes in a host matrix are less than 65%, OLED device external quantum efficiencies of up to 8.1% have been achieved at a luminance of 1000 cd/m2. Selection of a boron emitter with a gap of less than 0.01 eV between the singlet and triplet excited state enables the fabrication of a device with low efficiency roll-off and long lifetime. |
| Databáze: | OpenAIRE |
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