Nonconjugated Triptycene-Spaced Donor-Acceptor-Type Emitters Showing Thermally Activated Delayed Fluorescence via Both Intra- and Intermolecular Charge-Transfer Transitions

Gaole Dai; Ming Zhang; Kai Wang; Xiaochun Fan; Yizhong Shi; Dianming Sun; Wei Liu; Jiaxiong Chen; Jia Yu; Xuemei Ou; Shiyun Xiong; Caijun Zheng; Xiaohong Zhang

doi:10.1021/acsami.1c05646

Nonconjugated Triptycene-Spaced Donor-Acceptor-Type Emitters Showing Thermally Activated Delayed Fluorescence via Both Intra- and Intermolecular Charge-Transfer Transitions

ACS Appl Mater Interfaces. 2021 Jun 2;13(21):25193-25201. doi: 10.1021/acsami.1c05646. Epub 2021 May 20.

Authors

Gaole Dai¹, Ming Zhang², Kai Wang¹, Xiaochun Fan¹, Yizhong Shi¹, Dianming Sun¹, Wei Liu¹, Jiaxiong Chen¹, Jia Yu¹, Xuemei Ou¹, Shiyun Xiong¹, Caijun Zheng², Xiaohong Zhang¹

Affiliations

¹ Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, P. R. China.
² School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu, Sichuan 610054, P. R. China.

PMID: 34013735
DOI: 10.1021/acsami.1c05646

Abstract

Thermally activated delayed fluorescence (TADF) emitters have aroused considerable attention, particularly for their great potential in organic light-emitting diodes (OLEDs). In typical TADF molecules, intramolecular charge transfer (CT) between electron-donor (D) and electron-acceptor (A) moieties is the dominant transition. Actually, CT transitions can possibly occur between different molecules as well. Herein, we used a nonconjugated triptycene (TPE) moiety to space D and A moieties and developed two novel emitters tBuDMAC-TPE-TRZ and tBuDMAC-TPE-TTR to explore the roles of intra- and intermolecular CT transitions. Along with weak intramolecular CT transitions, intermolecular CT transitions are dominant for tBuDMAC-TPE-TRZ and tBuDMAC-TPE-TTR neat films. Particularly, tBuDMAC-TPE-TRZ showed a high maximum external quantum efficiency of 10.0% in a nondoped solution-processed OLED, which was evidently higher than that of a corresponding 10 wt % tBuDMAC-TPE-TRZ-doped OLED with 4,4',4″-tris(carbazol-9-yl)triphenylamine (TCTA) as the host matrix. The results prove that intermolecular CT transitions indeed participate in the CT transition process in these systems and they are helpful to enhance the electroluminescence performance of emitting systems with weak intramolecular CT transitions.

Keywords: intermolecular charge transfer; organic light-emitting diodes; solution-processed OLEDs; thermally activated delayed fluorescence; triptycene.