Study On Solar Cells Based On ZnO Nanotube Arrays

In this paper, well aligned ZnO nanorod array was fabricated on ITO substrate byelectrodeposition, and ZnO nanotube array was also obtained by electrochemical etchingof ZnO nanorod array in alkaline solution, and then a suitable thickness of CdTenanoparticle and P3MT layer were electrodeposited onto the walls of ZnO nanotube array.Finally, different kinds of electrodes based on ZnO nanotubes were made. Thecomposition、morphology and structure of electrode materials was determined andanalyzed by means of SEM、TEM、HRTEM、EDS and XRD. Photovoltaic properties ofelectrode materials were also studied.Electrodes such as CdTe/ZnO and P3MT/CdTe/ZnO were assembled respectivelywith platinized ITO counter electrodes to fabricate different kinds ofsemiconductor-sensitized solar cells. The effect of CdTe and P3MT layer thickness on thephotovoltaic properties were studied. The solar cell based on the CdTe（1.5h）/ZnOelectrode displayed the best photovoltaic property among devices based on CdTe（differenttimes）/ZnO electrodes, and its power conversion efficiency reached0.89%. When P3MTwas deposited on CdTe/ZnO electrodes, photovoltaic properties of solar cells based onthem were improved greatly. The energy conversion efficiency of the solar cell based onthe P3MT（2min）/CdTe（1.5h）/ZnO electrode reached1.20%, which was the highest amongall the devices. The significant improvement in photovoltaic property was attributed to thep-n heterojunction which was formed between the interface of CdTe and P3MT. The p-nheterojunction could facilitate the separation and restrain the recombination ofphotoelectrons and holes. The current-potential linear scanning curve forP3MT/CdTe/ZnO electrode proved the existence of p-n heterojunction.As a new p-type semiconductor, Cu₂O has been attracted more attention in recentlyyears. In this paper, Cu₂O nanoparticles were electrodeposited onto the walls of ZnOnanotube array to form a core-shell nanostructure. The morphology and structure ofelectrode materials were determined and analyzed by means of SEM、HRTEM and XRD.Photovoltaic properties of electrode materials were also studied. With prolonging theelectrodeposition time of Cu₂O, the particle size of cubic Cu₂O was increased from tensnanometer to hundreds nanometer，and the performance increased first and then decreased.When the electric charge of Cu₂O was1C, the electrode displayed the best photovoltaicproperty. The current-potential linear scaning curve for Cu₂O/ZnO electrode proved that a p-n heterojunction was formed between the interface of Cu₂O and ZnO. In addition, asolid state solar cell based on Cu₂O/ZnO photoelectrode and Au/Cu cathode wasfabricated, and its power conversion efficiency is0.013%. A futher research was alsoneeded in order to improve the photovoltaic property of this kind of solid state solar cells.