Xu Peng, Zhang Cai-Rong, Wu You-Zhi, Yuan Li-Hua, Chen Yu-Hong, Liu Zi-Jiang, Chen Hong-Shan
Department of Applied Physics, Lanzhou University of Technology, Lanzhou, Gansu 730050, China.
School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China.
J Phys Chem A. 2020 May 7;124(18):3626-3635. doi: 10.1021/acs.jpca.0c01746. Epub 2020 Apr 24.
Due to the role of dyes in dye-sensitized solar cells (DSSCs), designing novel dye sensitizers is an effective strategy to improve the power conversion efficiency. To this end, the fundamental issue is understanding the sensitizer's trilateral relationship among its molecular structure, optoelectronic properties, and photovoltaic performance. Considering the good performance of N-annulated perlyene dye sensitizers, the geometries, electronic structures, and excitations of the selected representative organic dye sensitizers C276, C277, and C278 as well as dyes adsorbed on TiO clusters were calculated in order to investigate the relationship between molecular structures and properties. It was found that fusing thienyl to N-annulated perlyene can elevate the highest occupied molecular orbital (HOMO) energy, reduce the orbital energy gap, increase the density of states, expand the HOMO to the benzothiadiazole moiety, enhance the charge transfer excitation, elongate the fluorescence lifetime, amplify the light harvesting efficiency, and induce a red-shift of the absorption spectra. The transition configurations and molecular orbitals of the dye-adsorbed systems support that the electron injection in DSSCs based on these dyes is a fast mode. Based on extensive analysis of the electronic structures and excitation properties of these dye sensitizers and the dye-adsorbed systems, we present new quantities as open-circuit voltage and short-circuit current density descriptors that celebrate the quantitative bridge between the photovoltaic parameters and the electronic structure-related properties in order to expose the relationship between properties and performance. The results of this work are critical for the design of novel dye sensitizers for solar cells.
由于染料在染料敏化太阳能电池（DSSC）中的作用，设计新型染料敏化剂是提高功率转换效率的有效策略。为此，根本问题是理解敏化剂在其分子结构、光电性质和光伏性能之间的三边关系。考虑到氮杂苝染料敏化剂的良好性能，计算了所选代表性有机染料敏化剂C276、C277和C278以及吸附在TiO簇上的染料的几何结构、电子结构和激发情况，以研究分子结构与性质之间 的关系。研究发现，将噻吩基与氮杂苝稠合可以提高最高占据分子轨道（HOMO）能量，减小轨道能隙，增加态密度，将HOMO扩展到苯并噻二唑部分，增强电荷转移激发，延长荧光寿命，提高光捕获效率，并导致吸收光谱红移。染料吸附体系的跃迁构型和分子轨道表明，基于这些染料的DSSC中的电子注入是一种快速模式。基于对这些染料敏化剂和染料吸附体系的电子结构和激发性质的广泛分析，我们提出了作为开路电压和短路电流密度描述符的新量，这些量建立了光伏参数与电子结构相关性质之间的定量桥梁，以揭示性质与性能之间的关系。这项工作的结果对于设计用于太阳能电池的新型染料敏化剂至关重要。
