T. Minemoto et al., Cu(In,Ga)Se-2 solar cells with controlled conduction band offset of window/Cu(In,Ga)Se-2 layers, J APPL PHYS, 89(12), 2001, pp. 8327-8330
Our group studied the effects of conduction band offset of window/Cu(In,Ga)
Se-2 (CIGS) layers on CIGS-based solar cell performance. To control the con
duction band offset, we considered the use of a window layer of Zn1-xMgxO t
hin film with a controllable band gap as an alternative to the conventional
window layer using CdS film. From the measurement of valence band offset b
etween Zn1-xMgxO/CIGS layers and the band gap of each layer, we confirmed t
hat the conduction band offset of Zn1-xMgxO/CIGS layers could be controlled
by changing the Mg content of the Zn1-xMgxO film. The CIGS-based solar cel
ls prepared for this study consisted of an ITO/Zn1-xMgxO/CIGS/Mo/soda-lime
glass structure. When the conduction band minimum of Zn1-xMgxO was higher t
han that of CIGS, the performance of CIGS-based solar cells with a Zn1-xMgx
O window layer was equivalent to that of CIGS-based solar cells with CdS wi
ndow layers. We confirmed that the control of the conduction band offset of
the window/CIGS layers decreases the majority carrier recombination via th
e Zn1-xMgxO/CIGS interface defects. (C) 2001 American Institute of Physics.