摘要
由于具有良好的光化学稳定性、在可见光区和近红外区的强吸光性等优点,方酸类染料是目前最具潜力的小分子有机太阳能电池给体材料之一.然而,其空穴迁移机制并不明确,较低的迁移率限制了器件光电转换效率的提升.结合第一性原理计算、Marcus电子转移理论、主方程模拟,系统研究了三氢-苯并吲哚啉方酸(USQ-BI)染料的电子结构、分子堆积模式以及电荷转移性质.结果表明,由于空穴迁移路径上交替出现两种不同的分子堆积模式,驱动力呈现正负交错的特征,克服正驱动力的过程为空穴迁移的决速步.据此,提出了降低驱动力绝对值以增大迁移率的理论策略.进一步研究发现,在一些位点上引入氰基可以显著提高空穴转移耦合强度,从而提高空穴迁移率.最后,对USQ-BI中电子转移过程的研究发现,由于较大的重组能导致较小的电子转移速率,该晶体不能作为好的电子传输材料.
Due to the advantages of good photochemical stability and strong light absorption in the visible and near-infrared regions,the squaraine dyes are one of the most prominent electron donor materials for small-molecule organic solar cells at present.However,the hole transport mechanism therein is yet to be uncovered,and the low hole mobility severely limits the enhancement of power conversion efficiency of the devices.By combining first-principle calculations,Marcus electron transfer theory and master equation simulations,the electronic structures,molecular stacking types and charge transfer properties of the 3H-benzo[e]indoline squaraine(USQ-BI)dyes were systematically investigated in this study.The results showed that due to the alternating occurrence of two different molecular stacking types,the driving force exhibited a positive-negative alternating character,and the process of overcoming the positive driving force was the rate-limiting step in the hole transport.As such,a theoretical strategy of increasing mobilities by reducing the absolute value of the driving force was proposed.Further investigations indicated that the introduction of cyano groups at some sites of the USQ-BI molecule could significantly improve the hole-transfer electronic coupling strength,and then improve the hole mobility.Finally,the study on the electron transfer process in the USQ-BI crystal showed that USQ-BI might not be a good electron transport material because of the small electron transfer rate caused by large reorganization energies.
作者
彭吉生
汪宇晨
裴政
梁万珍
赵仪
PENG Jisheng;WANG Yuchen;PEI Zheng;LIANG Wanzhen;ZHAO Yi(State Key Laboratory of Physical Chemistry of Solid Surfaces,Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry,College of Chemistry and Chemical Engineering,Xiamen University,Xiamen 361005,China)
出处
《厦门大学学报（自然科学版）》
CAS
CSCD
北大核心
2023年第1期22-30,共9页
Journal of Xiamen University：Natural Science
基金
国家自然科学基金(22033006,21833006)。
