A carbon nanotube-based transparent conductive substrate for flexible ZnO dye-sensitized solar cells

Abstract A transparent carbon nanotube (CNT)-coated polyethylenterephthalat film was used as conducting substrate for the photoanode of a flexible ZnO-based dye-sensitized solar cell (DSSC). The porous ZnO films were fabricated by an electrochemical deposition method at low temperature. Electrochemical impedance spectroscopy revealed that the CNT/ZnO interface adds to the overall impedance of the cell, leading to a higher series resistance compared to DSSCs based on substrates employing a transparent conducting oxide. Nevertheless, an overall conversion efficiency of 2.5% was obtained with porous ZnO films electrodeposited on the CNT substrate for 60 min. Thicker films led to an increased loss by recombination, which could not be compensated by faster electron transport due to the decrease of the light intensity inside the ZnO film with increasing distance from the back contact.