Pulse and Direct Current Electrodeposition of Zinc Oxide Layers for Solar Cells with Extra Thin Absorbers

The feasibility of one-dimensional (1D) nanostructured zinc oxide array pulse plating has been presented. An effect of the electrolyte composition, deposition regime and subsequent annealing on structure and optical properties of the electrodeposited ZnO layers has been approved by X-ray diffraction and spectrophotometric analysis. We have determined that for obtaining of ZnO arrays with strong (002) preferable growth orientation in the c-axis direction it is necessary to diminish adsorption of hydrogen and Cl-ions. It has been shown that such conditions are created in electrolyte that contains 0.05 M Zn(NO3)2 and 0.1 M NaNO3 during electrodeposition on FTO-coated glass substrates in pulse plating regime with rectangular impulses of cathode potential (20 ms on-time at Uon = -1.4 V and 30 ms off-time at Uoff = -0.8 V). Therefore, in this work we for the first time have demonstrated the successful growth of 1D ZnO nanostructures by pulse plating without using of templates. The novel electrodeposition technique gives possibilities for the manufacture of the ZnO arrays suitable for solar cells with extra thin absorbers.