https://doi.org/10.1051/epjap:1999228
A model for the open circuit voltage relaxation in Cu(In,Ga)Se2 heterojunction solar cells
1
Faculty of Physics, University of Oldenburg, 26111 Oldenburg, Germany
2
Institut für Physikalische Elektronik, Universität Stuttgart, Pfaffenwaldring
47, 70569 Stuttgart, Germany
Corresponding authors: thorsten.meyer@uni-oldenburg.de uwe.rau@ipe.uni-stuttgart.de
Received:
29
January
1999
Revised:
22
July
1999
Accepted:
22
July
1999
Published online: 15 October 1999
This article investigates the electronic transport properties of ZnO/ CdS/ Cu(In,Ga)Se2 heterojunction solar cells during and after illumination or forward bias in the dark. We observe a relaxation of the open circuit voltage under constant illumination as well as a relaxation of the voltage drop over the device under constant forward bias current in the dark. Both phenomena are accompanied by an increase of the sample capacitance. We introduce a general quantitative model concept for the open circuit voltage relaxation and related effects in heterojunction devices that explains the phenomena as a consequence of the persistent capture of charge carriers within the space charge region. We apply our concept to develop a specific quantitative model for the observed metastablity in Cu(In,Ga)Se2 heterojunction solar cells.
PACS: 73.40.Lq – Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions / 73.61.Ga – II-VI semiconductors / 72.40.+w – Photoconduction and photovoltaic effects
© EDP Sciences, 1999