Semitransparent CdTe solar cell with over 70% near-infrared transmittance

CdTe solar cell is a promising alternative to conventional silicon solar cells and it is quite potential to be utilized as a top sub-cell for tandem solar cells to improve the power conversion efficiency of the existing single-junction devices, whose efficiency has been approaching their practical efficiency limit. Thus, the research and development of semitransparent CdTe solar cells are urgently required. In this work, semitransparent CdTe solar cells were prepared by utilizing 900-nm-thick ultrathin CdTe absorber and CuCl/ITO transparent back contacts. The ultrathin CdTe in the present work was prepared by magnetron sputtering and the effects of substrate temperature and deposition ambient were extensively investigated. CdTe thin films with minimal dislocation density and lowest internal strain were fabricated at a substrate temperature of 235 degrees C with pure Ar atmosphere. The improved optical-electrical properties of CdTe absorber were then contributing on device performance, and as a result, we successfully fabricated a semitransparent CdTe solar cell with an optimal efficiency of 8.60%. It is worth noting that the transmittance around 1000 nm in the near-infrared region (NIR) is over 70%, which is the highest value among the as-reported semitransparent CdTe solar cells. The present work paves a way to optimize the performance and improve the optical transmittance of semitransparent CdTe solar cells so that it strongly supports their potential applications in bifacial and/or tandem configurations, building integrated photovoltaics, and so on.