Neodymium doped titania as photoanode and graphene oxide–CuS composite as counter electrode material in quantum dot solar cell

The enhanced photoresponse of commercial TiO2(C-TiO2) nanoparticles in quantum dot (QD) sensitized solar cells, when doped with neodymium (Nd), is explored for graphene oxide–copper sulphide (GO–CuS) composite material as counter electrode. The modification of C-TiO2and the preparation of GO–CuS were done by solid state and sonication methods respectively. The same were characterized by spectroscopy, microscopy, and cyclic voltammetry techniques. Results clearly indicate an enhanced conversion efficiency of ∼1.6 times over the undoped C-TiO2. UV and reflectance spectroscopy reveal that the dopants/defects/oxygen vacancies create midbands causing favorable surface electron states which act as electron traps suppressing recombination and the same is later detrapped leading to an efficient electron transfer. The retention of anatase phase, increase in particle size and decrease in band gap energy to visible range together with high surface area imparted by the GO to CuS in counter electrode facilitate good light harvesting and rapid enhanced electron transfer to redox system on doping. These findings make Nd–TiO2a good photoanode material and GO–CuS a good counter electrode in QD solar cells.