Enhancement of dye-sensitized solar cell efficiency through co-sensitization of thiophene-based organic compounds and metal-based N-719

Abstract

Synthesis of five novel thiophene-based metal-free organic dyes, named IS1-5, to study their photophysical, electrochemical properties and photovoltaic performance as sensitizers and co-sensitizers for DSSCs. Dyes IS-5 are cyanoacetanilide derivatives, which are distinguished by their small size, the simple preparation method, and the presence of multiple anchoring species (CO and CN) within their molecular structure. From their UV/Vis. spectra, IS-4 and IS-5 displayed the highest molar extinction coefficient with a bathochromic-shift to the intramolecular charge transfer band. In addition, to recognize the potential of HOMO level and the potential of LUMO level among all IS1-5 dyes, the cyclic voltammetry technique must be used. Their characteristics assert that all dyes possess the qualifications essential to be used as a sensitizer for dye-sensitized solar cells (DSSCs). Interestingly, over co-sensitization, all dyes showed better photovoltage values (VOC) than the standard dye N-719. Among Dyes IS1-5, co-sensitizer IS-5 showed the highest photoconversion efficiency (η) of (8.09%) compared to the standard dye N-719 (7.61%). Moreover, electrochemical impedance spectroscopy (EIS) asserts the impact of this dye on improving charge transfer in TiO2. Finally, density functional theory (DFT) has been studied for dyes IS1-5 using Guassian09 software and the outcomes comfortably agree with experimental results.

Keywords

• Thiophene
• Photoconversion efficiency
• Co-sensitization
• DFT