Abstract

Herein, eight new donor-π-acceptor organic dyes namely M1–M8 have been theoretically investigated for their potential in optoelectronic properties. The M1–M8 were designed through structural modification of π-conjugated bridge of reference reported molecule IC2. The designed molecules contain Indolo[3,2,1-jk]carbazole as core donor unit and end capped cyanoacrylic acid as acceptor unit. DFT and TDDFT calculations using B3LYP, CAM-B3LYP, ωB97XD and M062X functional were performed to evaluate the photophysical and photovoltaic properties. Results indicate that HOMO–LUMO energy gaps in M1–M8 have been found smaller than IC2. Among all, M7 is a material with lowest energy gap 2.61 eV, red shifted absorption wavelength value 436 nm. Results of the calculated redox potential of the ground state, vertical excitation energy of the dye, oxidation potential of the dye in the excited state, free energy change for electron injection, dye regeneration and open circuit photovoltage and light harvesting efficiency indicates that π-bridges in M1–M8 would show better power conversion efficiency than IC2. Especially, dye M7 with π-bridge 5-(thiazol-5yl)thiazole is found to be the most promising candidate for highly effective DSSCs properties. This theoretical framework may provide new ways for experimentalists to design high-performance DSSCs materials for optoelectronic applications.

Graphic Abstract

摘要

在本文中，从理论上研究了八种新型供体-π-受体有机染料M1 - M8的光电性能。的M1 - M8是通过参考π共轭桥的结构修饰设计报道分子IC2。设计的分子包含Indolo [3,2,1-jk]咔唑作为核心供体单元和封端的氰基丙烯酸作为受体单元。使用B3LYP，CAM-B3LYP，ωB97XD和M062X功能进行DFT和TDDFT计算，以评估光物理性质和光电性质。结果表明，发现M1 - M8中的HOMO-LUMO能隙小于IC2。其中，M7是具有最低能隙2.61 eV，红移吸收波长值为436 nm的材料。计算的基态氧化还原电势，染料的垂直激发能，染料在激发态下的氧化电势，电子注入的自由能变化，染料再生以及开路光电压和光收集效率的结果表明，π桥在M1 - M8会显示出比更高的电源转换效率IC2。特别是染料M7具有π-桥5-（噻唑-5基）噻唑的化合物被发现是高效DSSCs性能的最有希望的候选者。这个理论框架可以为实验人员设计用于光电应用的高性能DSSCs材料提供新的方法。

图形摘要