Photovoltaic performance of a Cd1−xMgxTe/CdS top-cell structure

In this paper we report the progress in developing a wide band gap alloy material based on CdTe to use as the top-cell absorber in tandem solar cells. High photovoltaic performance for a Cd1−xMgxTe/CdS top-cell was achieved by tuning the composition of the Cd1−xMgxTe film, and optimizing the device processing. We have carried out studies on the effect of vapor chloride treatment of the Cd1−xMgxTe/CdS device and the thermal annealing of the Cu/Au contacts on the opto-electronic properties of the device. With improved contact processing and post deposition treatments, we were able to achieve 9.3% efficiency for a 1.6eV band gap top-cell; Cd1−xMgxTe/CdS on conductive glass substrate. •Cd1−xMgxTe films obtained by co-evaporation of CdTe and Mg•Band gap of Cd1−xMgxTe can be easily tuned by verifying x.•Band gap of Cd1−xMgxTe is stable only for short annealing durations.•Obtained efficiency of a Cd1−xMgxTe based device with a band gap of 1.6eV is 9.3%.