Thiophene-bithiazole based metal-free dye as DSSC sensitizer: Effect of co-adsorbents on photovoltaic efficiency

Abstract

A new molecule consisting of a bithiazole chromophore sandwiched between two thiophenes, functionalized with benzothiophene unit at one end and cyanoacrylic acid at the other end (BT1) was synthesized, photophysical properties were studied and employed as a photosensitizer in dye-sensitized solar cells (DSSCs). The molecule exhibited an intense absorption in the UV-visible region with absorption extending up to 500 nm. The ground and excited state potentials of BT1 were calculated to be 1.29 and-0.65 V, respectively vs. NHE using cyclic voltammetry. The ground state energy level is more positive than the triiodide electrolyte and excited state energy level is considerably more negative than the TiO 2 satisfying the energetic requirements for a photosensitizer in DSSC. The solar cells fabricated from BT1 exhibited an efficiency of 1.13%. The effect of various co-adsorbents (CDCA,TP1 andTP2) on the DSSC performance was investigated in detail. In the presence of CDCA, the photovoltaic efficiency was enhanced to 1.25%, whereas, in the presence of TP1 and TP2, the efficiency lowered to 0.20% and 0.59%, respectively. The increased efficiency in the presence of CDCA could be attributed to the prevention of the aggregation of dye molecules induced by CDCA. On the other hand, TP1 and TP2 were found to be not as effective as CDCA to prevent aggregation leading to the lowering of photoconversion efficiency.

Investigation of effect of thiophene-2-acetic acid as an electron anchoring group for a photovoltaic device

“…The fluorescence emission maxima of the two photosensitizers Dye 1 and Dye 2 in the solution were 512 and 574, respectively. The fluorescence emission maxima of the those of thioindigo dyes were higher than the thiophen-based dyes such as, BT1 (451 nm) [27] due to the presence of the N,N-diparatolylaniline groups in the structure of thioindigo organic dyes.…”

“…The results in Table 2 show that the absorption peak shifted to longer wavelengths due to using the thiophene group as a stronger anchoring substituent [26] compared to acrylic substituents in Dye 1. The N,N-diparatolylaniline substituent has increased the max for Dye 2 compared with organic photosensitizer containing thiophene group such as BT1 with max around 388 nm [27]. The obtained dyes were coated on SnO 2 for DSSCs preparation.…”

Synthesis and Optoelectronic Properties of Thiophene‐Based Semiconducting Oligomers

“…Synthetic steps leading to the formation of oligomers were shown in Scheme . Synthesis of molecules from 1–6 were performed according to our previously reported procedures . Standard Stille coupling between 6 and 5,5′‐bis(tributylstannyl)‐2,2′‐bithiophene gave 7 , whereas the coupling between 6 and 2,5‐bis(trimethylstannyl)thieno[3,2‐b]thiophene gave 8.…”

Structure and Photoelectrical Properties of Natural Photoactive Dyes for Solar Cells

“…It is remarkable that the dyes play a crucial role in DSSCs because firstly they absorb sunlight [8], followed by injection of the excited electron into semiconductor. In addition to the use of dyes containing metal elements [9][10][11], the metal-free organic dyes have been widely applied to the field of DSSCs [12][13][14][15][16][17][18][19]. However, the shortcomings of high cost, environmental pollution and also expensive chemical synthesis process are worth the attention of the researchers [20].…”