Improved fill factor and open circuit voltage by crystalline selenium at the Cu(In,Ga)Se2/buffer layer interface in thin film solar cells

• Published in: Progress in photovoltaics 2010-06, Vol.18 (4), p.249-256
• Main Authors: Platzer-Björkman, C., Zabierowski, P., Pettersson, J., Törndahl, T., Edoff, M.
• Format: Article
• Language: English
• Subjects: Atomic structure; buffer layer; Buffer layers; CIGS; COPPER INDIUM SELENIDE; COPPER SELENIDE; Devices; ELECTRONIC PRODUCTS; interface; INTERFACES; MOLECULAR STRUCTURE; Open circuit voltage; ORGANIC COMPOUNDS; Photovoltaic cells; Selenium; Solar cells; thin film solar cells; THIN FILMS; Volatile organic compounds; VOLTAGE
• ISSN: 1062-7995; 1099-159X; 1099-159X
• DOI: 10.1002/pip.957

A surface treatment by evaporated selenium on Cu(In,Ga)Se2 (CIGS) is shown to improve open circuit voltage, Voc, and in some cases fill factor, FF, in solar cells with CdS, (Zn,Mg)O or Zn(O,S) buffer layers. Voc increases with increasing amount of crystalline Se, while FF improves only for small amounts. The improvements are counteracted by a decreasing short circuit current assigned to absorption in hexagonal Se. Improved efficiency is shown for device structures with (Zn,Mg)O and Zn(O,S) buffer layers by atomic layer deposition. Analysis by grazing incidence X‐ray diffraction and photoelectron spectroscopy show partial coverage of the CIGS surface by hexagonal selenium. The effects on device performance from replacing part of the CIGS/buffer interface area by a Se/buffer junction are discussed. Copyright © 2010 John Wiley & Sons, Ltd. A surface treatment by evaporated selenium on Cu(In,Ga)Se2 is shown to improve open circuit voltage, Voc, and in some cases fill factor, FF, in solar cells with CdS, (Zn,Mg)O or Zn(O,S) buffer layers. The improvements are counteracted by a decrease in short circuit current assigned to absorption in hexagonal Se. Improved efficiency is shown for device structures with (Zn,Mg)O and Zn(O,S) buffer layers by atomic layer deposition.