Characterization of Cu(In,Ga)Se₂ Solar Cell Fabrication Process by Photoluminescence

Abstract

Photoluminescence (PL), PL intensity mapping and time-resolved PL (TR-PL) studies have been applied to the Cu(In,Ga)Se 2 (CIGS) solar cell fabrication process. Measurements have been done just after the respective cell process for the preparation of the Al/ZnO:Al/ZnO/CdS/CIGS structure, in which CdS has been formed by the chemical-bath deposition (CBD) while undoped and Al-doped ZnO layers were deposited by RF magnetron sputtering. PL intensity does not change by depositions of CdS and undoped ZnO buffer layers. PL intensity decreases by the deposition of the ZnO:Al film due to the cell shunt at the edge. The electrical cell isolation by the mechanical scribing leads to the increase in PL intensity because of the formation of the hetero-junction under the open circuit condition. The decay curves of the as deposited CIGS film, CdS/ CIGS and ZnO/CdS/CIGS are non-exponential and composed of dominant fast decay and weak slow decay components. After the ZnO:Al deposition, PL decay is represented by the single exponential curve with long decay time. They are discussed in terms of the junction formation. PL intensity mapping after cell processes has been correlated with the solar cell performance. #