Liu Yun, Shao Di, Bai Xiaohui, Yang Zhenqing, Lin Chundan, Shao Changjin
State Key Laboratory of Heavy Oil Processing, Beijing Key Laboratory of Optical Detection Technology for Oil and Gas, and College of Science, China University of Petroleum, Beijing 102249, PR China.
State Key Laboratory of Heavy Oil Processing, Beijing Key Laboratory of Optical Detection Technology for Oil and Gas, and College of Science, China University of Petroleum, Beijing 102249, PR China; Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB30HE, United Kingdom.
Spectrochim Acta A Mol Biomol Spectrosc. 2017 May 15;179:227-232. doi: 10.1016/j.saa.2017.01.054. Epub 2017 Jan 26.
The cyano group (CN) of the acceptor in organic sensitizers plays an important role for highly efficient dye-sensitized solar cells. In this paper, three 5, 6-difluoro-2,1,3-benzothiadiazole (DFBTD) organic molecules with different number of CN units, named ME15, ME16 and ME17, were investigated by the density functional theory (DFT) and time-dependent DFT (TDDFT). We analyzed the CNs effects on the electronic structures, optical properties, adsorption modes and electron transfer and injection. The result shows that ME17 has the largest maximum absorption wavelength (λ) among these new designed dyes due to the strong electron withdrawing ability of two CNs. In addition, CN greatly influence the adsorption modes of dye/TiO and electron injection mechanism. ME16 with one CN also has good optical absorption properties and its acceptor has the strongest coupling strength with the TiO semiconductor which is favorable for electron transfer and injection. Thus, we believe that the number of CN groups in acceptor should be moderate and one CN in D-A-π-A structure dyes may be the more appropriate focusing on the light harvesting ability, electron transfer and electron injection.
有机敏化剂中受体的氰基（CN）对高效染料敏化太阳能电池起着重要作用。本文采用密度泛函理论（DFT）和含时密度泛函理论（TDDFT）研究了三种具有不同CN单元数量的5,6-二氟-2,1,3-苯并噻二唑（DFBTD）有机分子，命名为ME15、ME16和ME17。我们分析了CN对电子结构、光学性质、吸附模式以及电子转移和注入的影响。结果表明，由于两个CN的强吸电子能力，ME17在这些新设计的染料中具有最大的最大吸收波长（λ）。此外，CN对染料/TiO的吸附模式和电子注入机制有很大影响。具有一个CN的ME16也具有良好的光吸收性能，其受体与TiO半导体具有最强的耦合强度，有利于电子转移和注入。因此，我们认为受体中CN基团的数量应适中，从光捕获能力、电子转移和电子注入的角度来看，D - A - π - A结构染料中的一个CN可能更为合适。
