Singlet Fission in a Pyrrole-Fused Cross-Conjugated Skeleton with Adaptive Aromaticity

Long Wang; Lu Lin; Jingjing Yang; Yishi Wu; Hua Wang; Jun Zhu; Jiannian Yao; Hongbing Fu

doi:10.1021/jacs.0c00089

Singlet Fission in a Pyrrole-Fused Cross-Conjugated Skeleton with Adaptive Aromaticity

J Am Chem Soc. 2020 Jun 10;142(23):10235-10239. doi: 10.1021/jacs.0c00089. Epub 2020 May 27.

Authors

Long Wang¹, Lu Lin², Jingjing Yang¹, Yishi Wu³, Hua Wang¹, Jun Zhu², Jiannian Yao⁴, Hongbing Fu^{3

4}

Affiliations

¹ Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China.
² State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
³ Beijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry, Capital Normal University, Beijing 100048, China.
⁴ Institute of Molecular Plus, School of Chemical Engineering and Technology, Tianjin University, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China.

PMID: 32437140
DOI: 10.1021/jacs.0c00089

Abstract

Singlet fission (SF) materials hold the potential to increase the power conversion efficiency of solar cells by reducing the thermalization of high-energy excited states. The major hurdle in realizing this potential is the limited scope of SF-active materials with high fission efficiency, suitable energy levels, and sufficient chemical stability. Herein, using theoretical calculation and time-resolved spectroscopy, we developed a highly stable SF material based on dipyrrolonaphthyridinedione (DPND), a pyrrole-fused cross-conjugated skeleton with a distinctive adaptive aromaticity (dual aromaticity) character. The embedded pyrrole ring with 4n+2 π-electron features aromaticity in the ground state, while the dipole resonance of the amide bonds promotes a 4n π-electron Baird's aromaticity in the triplet state. Such an adaptive aromaticity renders the molecule efficient for the SF process [E(S₁) ≥ 2E(T₁)] without compromising its stability. Up to 173% triplet yield, strong blue-green light absorption, and suitable triplet energy of 1.2 eV, as well as excellent stability, make DPND a promising SF sensitizer toward practical applications.