DFT/TD-DFT study of novel T shaped phenothiazine-based organic dyes for dye-sensitized solar cells applications

Zhijie Xu; Yuanyuan Li; Wenjiong Zhang; Shundong Yuan; Lanzhong Hao; Tao Xu; Xiaoqing Lu

doi:10.1016/j.saa.2019.01.002

DFT/TD-DFT study of novel T shaped phenothiazine-based organic dyes for dye-sensitized solar cells applications

Spectrochim Acta A Mol Biomol Spectrosc. 2019 Apr 5:212:272-280. doi: 10.1016/j.saa.2019.01.002. Epub 2019 Jan 3.

Authors

Zhijie Xu¹, Yuanyuan Li², Wenjiong Zhang³, Shundong Yuan², Lanzhong Hao², Tao Xu³, Xiaoqing Lu⁴

Affiliations

¹ College of Science, China University of Petroleum, Qingdao, Shandong 266580, PR China; Key Laboratory of New Energy Physics and Materials in University of Shandong, China University of Petroleum, Qingdao, Shandong 266580, PR China. Electronic address: xuzj@upc.edu.cn.
² College of Science, China University of Petroleum, Qingdao, Shandong 266580, PR China; Key Laboratory of New Energy Physics and Materials in University of Shandong, China University of Petroleum, Qingdao, Shandong 266580, PR China.
³ College of Science, China University of Petroleum, Qingdao, Shandong 266580, PR China.
⁴ College of Science, China University of Petroleum, Qingdao, Shandong 266580, PR China; Key Laboratory of New Energy Physics and Materials in University of Shandong, China University of Petroleum, Qingdao, Shandong 266580, PR China. Electronic address: luxq@upc.edu.cn.

PMID: 30658281
DOI: 10.1016/j.saa.2019.01.002

Abstract

Five novel T shaped phenothiazine-based organic dyes DTTP1~5 with different spacers at N (10) position were designed. The geometries, electronic structures, absorption spectra, electron transfer and injection properties of these isolated dyes and dye/(TiO₂)₉ systems were investigated via density functional theory (DFT) and time dependent density functional theory (TD-DFT) calculation. The optimized geometries indicate that these T shaped dyes show non-planar conformations, which are helpful in suppressing the close intermolecular π-π aggregation in device and enhancing thermal stability. The calculated results indicate that type of π-conjugated spacers can affect the molecular absorption spectra. Introduction of thiophene-benzothiadizole-thiophene unit as π-conjugated spacer can most effectively shift the light absorption to near infrared region and enhance the light harvesting efficiency (LHE). Moreover, it is found that these dyes show a good performance of electron injection and dye regeneration owing to the proper electron injection driving force (ΔG_inject) and dye regeneration driving force (ΔG_reg). The theoretical results reveal that these dyes could be used as potential sensitizers for DSSCs, and DTTP4 would be the most plausible sensitizer for high-efficiency DSSCs due to the narrow HOMO-LUMO energy gap (Δ_H-L), broad absorption spectrum, high LHE value, and large dipole moment (μ_normal).

Keywords: Density functional theory (DFT); Dye-sensitized solar cells (DSSCs); Phenothiazine; Time dependent density functional theory (TD-DFT); π-Conjugated spacer.