Effect of thiophene rings rigidity on dye-sensitized solar cell performance. Dithienothiophene versus terthiophene as π− donor moiety
Samir Al-Taweel, Salah A. Al‐Trawneh, Hmoud Al-Dmour, Osamah Al-Gzawat, Wasim Alhalasah, Marwan S. Mousa
Abstract
Solar cells are fabricated based on two new dyes. Dye acts as an additive to thin layer interface. The effect of the π -conjugated rigidity of the thiophene rings on the photovoltaic characteristics has been investigated. The structures of the dye 1 was based on dithieno [3,2- b :2′,3′- d ] thiophene-2-cyanoacrylic acid, while dye 2 was based on [2,2':5′,2″-terthiophene]-5-cyanoacrylic acid and were confirmed by elemental analysis, mass spectrometry, 1 H NMR and 13 C NMR spectral data. The P3HT/dye 1/nc-TiO 2 solar cell produced the highest efficiency of 0.3 % with an open circuit voltage of 0.7 V compared to dye 2 solar cell. This has been attributed to the difference in energy levels of the dyes and location of their HOMO relative to conduction and valence bands of nc-TiO 2 . The dye 1 has rigid fused thiophene rings and its HOMO is located between valence band of TiO 2 and HOMO of P3HT which leads to improve the charge carrier separation and increase the current density to reach 1.2 mA/cm 2 .