The development of suitable host materials for application to an emitter is of significant importance for high-efficiency organic light-emitting diodes (OLEDs). In this study, we successfully synthesized poly(9,9-diphenyl-10-(4-vinylbenzyl)-9,10-dihydroacridine) (P(Bn-DPAc)) as a polymer donor and 2-(4′-(tert-butyl)-[1,1′-biphenyl]-4-yl)-4,6-diphenyl-1,3,5-triazine (tPTRZ) as a small-molecule acceptor. A blend of P(Bn-DPAc) and tPTRZ was used as the host material in solution-processed green thermally activated delayed fluorescence OLEDs (TADF-OLEDs). The P(Bn-DPAc)-tPTRZ blend showed a new red-shifted peak in the photoluminescence spectrum, suggesting the possibility of exciplex formation. The polymer-mixed host film showed a fine surface morphology, a well-formed exciplex in the bulk state, and good charge balance. The OLED fabricated with the as-prepared mixed host (P(Bn-DPAc) : tPTRZ = 1 : 1 wt ratio) and 2,4,5,6-tetra(3,6-di-tert-butylcarbazol-9-yl)-1,3-dicyanobenzene (t4CzIPN) emitter exhibited a high current efficiency of 107.3 cd A−1 and a maximum external quantum efficiency (EQE) of 31.2%. The OLED fabricated with the mixed host demonstrated better performance compared to the device with a unipolar host P(Bn-DPAc).
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation (NRF) of Korea (no. NRF2019R1A2C2002647 and NRF2019R1A6A1A11044070) and LG Display Co. Limited (Q1927051, 2020). The authors also thank the Korea Basic Science Institute in Seoul for allowing them to use the MALDI-TOF MS instrument and the Institute for Basic Science (IBS, Korea) for allowing them to obtain nuclear magnetic resonance data (NMR; Ascend 500, Bruker).
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ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics