Enhancing the performance of hybrid nanocrystalline metal oxides / polymer solar cells using dye as interface modifier

Abstract

Hybrid Polymer / Metal oxide nanocomposite is a good and simple model system to study the effects of interfacial properties and film morphology on the performance of bulk heterojunction solar cells1-3 . Considerable interest has been paid on these hybrid solar cells for more than two decades because of the expertise knowledge generated with this system which has proved4 to be valuable in improving the performance of other organic based solar cells5,6 such as dye sensitized and perovskite solar cells6 . This talk reviews a range of dyes, including a novel thiophene 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) and Ru dyes, that have been applied to improve the performance of hybrid metal oxide / polymer 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 control7 . 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 dye8 . 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.