Performance of Dye-Sensitized Solar Cells Based on MWCNT/TiO2-xNx Nanocomposite Electrodes

Multiwall carbon nanotube (MWCNT) fibrils were introduced into TiO2-xNx photoelectrodes to enhance charge collection efficiency as charge-transport pathways. For comparison, we also synthesized MWCNT/TiO2 nanocomposites to fabricate dye-sensitized solar cells (DSCs). The effect of MWCNTs on the photovoltaic performance of the DSCs was studied in detail. The performance of DSCs based on MWCNT/TiO2-xNx differs significantly from that of MWCNT/TiO2 photoelectrodes. A high energy conversion efficiency of 7.66% was achieved in the dye-sensitized MWCNT/TiO2 nanocomposites solar cells. The results show that remarkable enhancement of ca. 33% and ca. 40% in the conversion efficiency (eta) and short-circuit photocurrent density (J(sc)), respectively, occurrs for the DSCs based on MWCNT/TiO2 than those made of pure TiO2 electrodes. The energy conversion efficiency of DSCs based on TiO2-xNx electrodes was 6.98%, which is similar to that of MWCNT/TiO2-xNx DSCs (6.88%-5.17%). We also investigated the charge collection efficiency, electron transport, electron lifetime, and photocurrent transient behavior by electrochemical analysis. The introduced MWCNTs exhibit a smaller sheet resistance and electron transfer resistance, as well as a longer electron lifetime. A 20% enhancement in the charge collection efficiency is achieved in the nanocomposite DSCs.