Deposition and Characterization of Copper Chalcopyrite Based Solar Cells using Electrochemical Techniques

摘要

Cu(In,Ga)Se_2 films were electrodeposited on molybdenum substrates from a single pH buffered bath and annealed in a reducing selenium atmosphere. The opto-electronic properties of the films were characterized using a potentiostatically-controlled three electrode setup and an electrolyte contact. Pulsed illumination was used to determine the carrier type and the speed of photoresponse. Chopped monochromatic illumination was used to measure photocurrent spectra. The electrodeposited copper chalcopyrite films were compared with films prepared by sputtering and spraying techniques. All electrodeposited films gave p-type photoresponses, and the sputtered film had the highest photocurrent. Optimum cyanide etch times to illicit the maximum photocurrent response were different for each material. The band gap of electrodeposited CuInSe_2 was 0.95 eV, which was slightly lower than that of the sputtered film. The electrodeposited Cu(In,Ga)Se_2 material gave a smaller photo-response but its band gap appeared to be similar to that of CuInSe_2. The best device based on an electrodeposited absorber layer had an efficiency of 4.5 %.