Low temperature electrodeposition of zinc oxide layers as transparent conducting oxide window layers for CIGS solar cells

Electrodeposition of zinc oxide layers has been carried out in simple aqueous solutions at 80°C in presence of zinc ions and dissolved oxygen. Extrinsic n type doping has been proven to be effective by anionic substitution of oxygen by chlorine, using chloride containing electrolytes. Doping level upper values up to 9.10¹⁹ cm^-3 have been obtained, associated with lateral resistivies in the 2-5 10^-3 ¿.cm. Optical transmission and Raman spectra confirm extrinsic doping. Prototype devices with record efficiency of 15.8% on small area (0.1 cm²) has been fabricated with ED-ZnO:Cl as proof of concept of using electrodeposited TCO layers as an alternative to vacuum based present technologies. Time stability is identified as a key issue for future development.