13.7 efficient Zn Se,OH x Cu In,Ga S,Se 2 thin film solar cell

Cu In,Ga Se2 CIGS and related semiconducting compounds have demonstrated their high potential for high efficiency thin film solar cells. The highest efficiency for CIGS based thin film solar cells has been achieved with CdS buffer layers prepared by a solution growth method known as chemical bath deposition CBD . With the aim of developing Cd free chalcopyrite based thin film solar cells, Zn Se,OH x buffer layers were deposited by CBD on polycrystalline Cu In,Ga S,Se 2 CIGSS . A total area conversion efficiency of 13 7 was certified by the Frauenhofer Institute for Solar Energy Systems. The CIGSS absorber was fabricated by Siemens Solar Industries California . For device optimization, the thickness and good surface coverage were controlled by XPS UPS photoemission spectroscopy. A Zn Se,OH x thickness below 7 nm has been found to be optimum for achieving a homogeneous and compact buffer film on CIGSS, with open circuit photovoltage Voc 535 mV, fill factor FF 70 76 and a high short circuit photocurrent density Jsc 36 1 mA cm amp; 8722;