CdTe-based photovoltaics using a CdTe/CdSe/CdTe absorber layer structure

One of the recent improvements in CdTe photovoltaics has been the inclusion of a CdSexTe1-x (CST) layer at the front interface of the absorber. The CST layer has a lower bandgap than CdTe, leading to increased current, whilst there is evidence that Se aids defect passivation which improves voltage. In this work we make use of a CdTe(A)/CdSe/CdTe(B) “andwich” structure with the aim of producing CdTe-based devices with a U-shaped bandgap profile. Highest device performances were achieved for CdTe(A) thicknesses in the range 0 nm to 100 nm, above which performance declined due to delamination from the substrate. Whilst the EQE curves did not indicate a U-shaped profile, the sandwich structure did enable higher CdSe incorporation into the CST layer.