Influence of donor and acceptor groups on the S-T energy gap for thermally activated delayed fluorescence emitters

ABSTRACT

Molecules composed of different donors and acceptors are theoretically designed as potential thermally activated delayed fluorescence emitters, and their singlet–triplet (S-T) energy gap is studied using the optimal Hartree–Fork method. It is found that the S-T energy gap is in reverse proportional to the electron-donating ability. Stronger electron-donating ability of donors will induce smaller highest occupied molecular orbital–lowest unoccupied molecular orbital overlap and also a smaller S-T energy gap. Based on our calculation results, three molecules are proposed to have great potential to be used as thermally activated delayed fluorescence emitters in organic light-emitting diodes.

KEYWORDS:

• Thermally activated delayed fluorescence
• energy gap between the singlet state and triplet state
• optimal Hartree-Fork functional

Acknowledgments

This work is supported by the National Science Foundation of Chian [grant number 11374195], [grant number 214031330]. Thanks to the supporting of Taishan Scholar Project of Shandong Province and the Scientific Research Foundation of Shandong Normal University. Thanks to the supporting of the Promotive Research Fund for Excellent Young and Middle-aged Scientists of Shandong Province [grant number BS2014CL001] and the General Financial Grant from the China Postdoctoral Science Foundation [grant number 2014M560571]. Great thanks to Professor Yi Luo, Zhigang Shuai, Qian Peng and Qisheng Zhang for their helpful suggestion and discussion in the detail calculation.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is supported by the National Natural Science Foundation of China [grant number 11374195],[grant number 21403133]. Thanks to the supporting of Taishan Scholar Project of Shandong Province and the Scientific Research Foundation of Shandong Normal University. Thanks to the supporting of the Promotive Research Fund for Excellent Young and Middle-aged Scientists of Shandong Province [grant number BS2014CL001] and the General Financial Grant from the China Postdoctoral Science Foundation [grant number 2014M560571].