Wang Long, Lin Lu, Yang Jingjing, Wu Yishi, Wang Hua, Zhu Jun, Yao Jiannian, Fu Hongbing
Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China.
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.
J Am Chem Soc. 2020 Jun 10;142(23):10235-10239. doi: 10.1021/jacs.0c00089. Epub 2020 May 27.
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 4+2 π-electron features aromaticity in the ground state, while the dipole resonance of the amide bonds promotes a 4 π-electron Baird's aromaticity in the triplet state. Such an adaptive aromaticity renders the molecule efficient for the SF process [(S) ≥ 2(T)] 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.
单线态裂变（SF）材料具有通过减少高能激发态的热化来提高太阳能电池功率转换效率的潜力。实现这一潜力的主要障碍是具有高裂变效率、合适能级和足够化学稳定性的SF活性材料的范围有限。在此，我们利用理论计算和时间分辨光谱，基于二吡咯并萘啶二酮（DPND）开发了一种高度稳定的SF材料，DPND是一种具有独特适应性芳香性（双芳香性）特征的吡咯稠合交叉共轭骨架。具有4+2 π电子特征的嵌入吡咯环在基态具有芳香性，而酰胺键的偶极共振在三重态促进4 π电子的贝尔德芳香性。这种适应性芳香性使分子在不影响其稳定性的情况下对SF过程高效[(S) ≥ 2(T)]。高达173%的三重态产率、强烈的蓝绿光吸收、1.2 eV的合适三重态能量以及出色的稳定性，使DPND成为一种有望用于实际应用的SF敏化剂。
