Author : Mahfouz Ali Saeed
Publisher :
ISBN 13 :
Total Pages : 187 pages
Book Rating : 4.:/5 (115 download)
Book Synopsis Electrochemical Fabrication of Thin Film Photovoltaic Devices (CIGS & CIGSS) by : Mahfouz Ali Saeed
Download or read book Electrochemical Fabrication of Thin Film Photovoltaic Devices (CIGS & CIGSS) written by Mahfouz Ali Saeed and published by . This book was released on 2014 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt: Copper Indium Gallium Selenium (CIGS) films are attractive for photovoltaic applications due to their high optical absorption coefficient. Generation of CIGS films by electrodeposition is particularly appealing due to the relatively low capital cost and the relatively high throughput. Numerous publications address the electrodeposition of CIGS; however, very few recognize the significance of transport, and consequently, deposition following published processes often leads to deficient films. We introduce here a new electrolyte composition, which is far more dilute than systems that had been previously described, and which yields much improved CIGS films. The electrolyte consists of: 0.4-0.6 mM CuCl2-H2O; 0.28-0.5 mM InCl3; 0.6-0.85 mM H2SeO3; and 0.35-0.6 mM GaCl3. PHydrion was used as buffer, and LiCl was used as a supporting electrolyte. Deposition experiments, under ambient temperature and pH=1.9 were carried on a rotating disk electrode which enabled to quantitatively control the transport rates. While the conventional electrolyte, which was ten times more concentrated yielded a powdery deposit which was shed into the electrolyte, the new, low concentration electrolyte produced in the preferred potential interval of -0.64 = E = -0.76 V/NHE, smooth deposit, with uniform composition in the desired range across a broad rotation speeds. We further extend the deposition process to the generation of Cu(In,Ga)(S,Se)2 [CIGSS] which offers potential advantages over CuInGaSe2 [CIGS] as a photovoltaic film due to its wider band-gap. Previously reported CIGSS fabrication requires elements addition from the vapor phase -- a slow and difficult to control process. Our electrolyte for the electrodeposition of CIGSS is similar in composition to that used for CIGS electrodeposition, however, it contains also 0.35 mM Na2S2O3, as a source for sulfur. The process provides the CIGSS compound in the desired stoichiometry without requiring elements addition from the vapor phase during annealing. Lastly, we introduce new electrochemical processes for the generation of complete CIGS and CIGSS functional photovoltaic devices, based entirely on electroplating. In addition to the absorber layer, electrochemical processes for the electrodeposition of the cadmium sulfide, and the pure and doped zinc oxide layers are described. The substrate has been stainless-steel coated with a molybdenum barrier layer, enabling continuous strip plating. Complete electrodeposited devices were generated and tested exhibiting efficiencies ranging from 2 to 6%. This is the first that such a comprehensive process had been described, leading the way to a potential fabrication of an entire device using an electrochemical route, enabling effective manufacturing integration and scaling.
