Evaluation of Zn[BOND]Sn[BOND]O buffer layers for CuIn0.5Ga0.5Se2 solar cells



Thin Zn[BOND]Sn[BOND]O films are evaluated as new buffer layer material for Cu(In,Ga)Se2-based solar cell devices. A maximum conversion efficiency of 13.8% (Voc = 691 mV, Jsc(QE) = 27.9 mA/cm2, and FF = 71.6%) is reached for a solar cell using the Zn[BOND]Sn[BOND]O buffer layer which is comparable to the efficiency of 13.5% (Voc = 706 mV, Jsc(QE) = 26.3 mA/cm2, and FF = 72.9%) for a cell using the standard reference CdS buffer layer. The open circuit voltage (Voc) and the fill factor (FF) are found to increase with increasing tin content until an optimum in both parameters is reached for Sn/(Zn + Sn) values around 0.3–0.4. Copyright © 2010 John Wiley & Sons, Ltd.