A Quarterthiophene-Based Dye as an Efficient Interface Modifier for Hybrid Titanium Dioxide/Poly(3-hexylthiophene)(P3HT) Solar Cells

This work focuses on studying the influence of dyes, including a 3-hexylthiophene derivative dye with a cyanoacrylic acid group ((E)-2-cyano-3-(3′,3′′,3′′′-trihexyl-[2,2′:5′,2′′:5′′,2′′′- quaterthiophene]-5-yl) acrylicacid)(4T), on the photovoltaic performance of titanium dioxide (TiO2) / poly(3-hexyl thiophene)(P3HT) solar cells. The insertion of dye at the interface improves the efficiency regardless of the dye used. However, 4T dye significantly improves the efficiency by a factor of three when compared to the corresponding control. This improvement is mainly due to increase in short circuit current density (JSC), which is consistent with higher hole-mobility reported in TiO2 / P3HT nanocomposite with 4T dye. Optical absorption data further reveals that 4T extends the spectral response of the TiO2 / P3HT nanocomposite which could also enhance the JSC. The reduced dark current upon dye insertion ensures that the carrier recombination is controlled at the interface and this in turn increased the open circuit voltage. Optimized hybrid TiO2 / P3HT device with 4T dye as an interface modifier showed average efficiency over 2 % under simulated irradiation of 100 mWcm-2 (1 sun) with Air Mass 1.5 filter.