Optical Absorption and Electron Injection of 4-(Cyanomethyl)benzoic Acid Based Dyes: A DFT Study

Yuehua Zhang,Runzhou Su,Yuanzuo Li,Penghui Ren,Meiyu Zhao

doi:10.1155/2015/402746

Abstract

Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations were carried out to study the ground state geometries, electronic structures, and absorption spectra of 4-(cyanomethyl)benzoic acid based dyes (AG1 and AG2) used for dye-sensitized solar cells (DSSCs). The excited states properties and the thermodynamical parameters of electron injection were studied. The results showed that (a) two dyes have uncoplanar structures along the donor unit and conjugated bridge space, (b) two sensitizers exhibited intense absorption in the UV-Vis region, and (c) the excited state oxidation potential was higher than the conduction band edge of TiO2photoanode. As a result, a solar cell based on the 4-(cyanomethyl)benzoic acid based dyes exhibited well photovoltaic performance. Furthermore, nine dyes were designed on the basis of AG1 and AG2 to improve optical response and electron injection.

Highlights

Since O’Regan and Grätzel reported the Dye-sensitized solar cells (DSSCs) [1], dye-sensitized solar cells (DSSCs) used as devices that convert visible light into electricity based on the photosensitization of wide band gap metal oxide semiconductors have attracted wide interest as a low cost of solar energy conversion
The steady efficiency of the DSSCs is kept by a polypyridyl ruthenium sensitizer [2, 5,6,7]; we have to face the practical problems of ruthenium sensitizer utility, such as a very expensive cost
Geometric optimizations of two molecules were performed with density functional theory (DFT) [29], using B3LYP

Summary

Introduction

Since O’Regan and Grätzel reported the Dye-sensitized solar cells (DSSCs) [1], DSSCs used as devices that convert visible light into electricity based on the photosensitization of wide band gap metal oxide semiconductors have attracted wide interest as a low cost of solar energy conversion. In terms of metalfree DSSCs, donor-π-bridge-acceptor (D-π-A) is a typical structure Various organic dyes, such as coumarin [8, 9], porphyrins [7, 10] phenylene [11], carbazole dyes [12, 13], indoline dyes [14, 15], and bis-dimethyl fluoroaniline (JKs)

Methods

Results

Conclusion