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Theoretical Study of Carbazole Dimers: Does Carbazole Form an Excimer That Undermines the Performance of Organic Light Emitting Diodes?
  • Kyungeon Lee,
  • Dongwook Kim
Kyungeon Lee
Kyonggi University
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Dongwook Kim
Kyonggi University
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Abstract

Carbazole (Cz) dimers in various cofacial conformations, including staggered (Stg), anti, and syn, were explored by means of ab initio calculations at SOS-MP2, SOS-CIS(D0), and additional coupled cluster calculation levels. As in other π-conjugated molecules, strong Cz excimers form in the syn conformation in both the S1 and T1 states, leading to significantly reduced optical excitation energies, whereas the dimers in the Stg and anti conformations, upon excitation, remain as simple excited dimers, showing similar optical energy gaps to that of the monomer. Being far more stable in the ground state, however, the Stg dimer turned out to be nearly isoenergetic to the syn dimer in the S1 state, and even more stable in the T1 state. In addition, a considerable potential energy barrier between the syn and Stg dimers was found in the calculated S1-state potential energy surface. Given that the ground-state intermolecular interactions are expected to govern the dimer conformations of Cz-based materials in the solid-state films of organic electronics, these results strongly demonstrate that the electronic excitation of Cz dimers do not necessarily lead to the strong excimer formation, unless Cz molecules were forced to be arranged in the syn conformation.

Peer review status:ACCEPTED

31 Dec 2019Submitted to International Journal of Quantum Chemistry
02 Jan 2020Submission Checks Completed
02 Jan 2020Assigned to Editor
20 Jan 2020Reviewer(s) Assigned
04 Feb 2020Review(s) Completed, Editorial Evaluation Pending
04 Feb 2020Editorial Decision: Revise Major
10 Apr 20201st Revision Received
13 Apr 2020Assigned to Editor
13 Apr 2020Submission Checks Completed
04 May 2020Reviewer(s) Assigned
20 May 2020Review(s) Completed, Editorial Evaluation Pending
26 May 2020Editorial Decision: Revise Minor
29 May 20202nd Revision Received
29 May 2020Submission Checks Completed
29 May 2020Assigned to Editor
02 Jun 2020Reviewer(s) Assigned
02 Jun 2020Review(s) Completed, Editorial Evaluation Pending
02 Jun 2020Editorial Decision: Accept