Te Solar Cells for tandem devices*

Wide bandgap Cd_1-xZn_xTe and Cd_1-xMg_xTe have drawn attention as top cells in tandem devices. These materials offer flexibility of tuning the band gap over a wide range by controlling the Zn (or Mg) concentration in CdTe with little alteration to its properties. Historically, CdS has been extensively used as a heterojunction partner for these devices. However, these devices show significantly low open circuit voltage than expected for wide bandgap absorbers due to poor band alignment at the CdS-absorber interface. Recent work shows that, by using wide band gap oxides to create this energetic “spike” at the window layer-absorber interface, device performance can be significantly improved. In this study, we will use SCAPS 1D software to model the wider band gap Cd_1-xZn_xTe and Cd_1-xMg_xTe devices to determine the appropriate alignment between the absorber and the window layer. We will also investigate how the material properties of TCO and window layer will affect the front contact alignment to determine the optimized device structure for high efficiency Cd_1-xZn_xTe and Cd_1-xMg_xTe.