Single-walled carbon nanotube thin-film counter electrodes for indium tin oxide-free plastic dye solar cells

The use of a thin carbon nanotube (CNT) counter electrode (CE) on plastic in a dye solar cell (DSC) is demonstrated as an alternative to expensive indium tin oxide and platinum materials. Optically transparent, single-walled CNT films synthesized by the aerosol CVD method and dry-printed on PET plastic substrates functioned as both the catalyst and conducting layer of the DSC CE. The best charge-transfer resistances and sheet resistances for the random network-type film were around 89Ωcm2 and 60Ω∕□ , respectively, making them suitable for low-intensity DSC applications. A solar cell efficiency of 2.5% was reached at an illumination of 8mW/cm2 . The photocurrent generation of the cells was found to decrease when a non-purified CNT-CE was used. The electrochemical removal of iron catalyst particles from the CNT films reduced the detrimental effect and stabilized the performance of the DSC.