SPLTRAK Abstract Submission
Alternative Rear Contacts for Ultrathin CdSexTe1-x Solar Cells
Bérengère Frouin1, Andrea Cattoni1, John Moseley2, David Albin2, Joel Duenow2, Abderrahime Sekkat3, David Muñoz-Rojas3, Stéphane Collin1
1Centre de Nanosciences et Nanotechnologies (C2N), CNRS, Université Paris-Saclay, Palaiseau, France
/2National Renewable Energy Laboratory (NREL), Boulder, CO, United States
/3Université Grenoble Alpes, CNRS, Grenoble INP, Laboratoire des Matériaux et du Génie Physique (LMGP), Grenoble, France

CdTe solar cells have reached a remarkable efficiency of 22.1% due to several key improvements over the years. The back contact has become a cornerstone for further developments toward higher efficiencies and for reduction of material usage. In this work, we investigate alternative back contacts on conventional and thin CdSeTe solar cells. First, we compare the performance of solar cells with different metal (Au, Ag) planar back contacts with and without a thin (1 nm) alumina passivation layer. Second, we present preliminary results of a back contact made of a p-type transparent conductive oxide (Cu2O). Third, we compare 800 nm-thick and 3.45 µm-thick CdSeTe solar cells, and we refine optical models to accurately simulate EQE measurements of both devices. Last, we introduce nanostructured back contact to further reduce the thickness of CdTe solar cells. We show optimized designs that exhibit efficient light-trapping in 200 nm-thick CdTe solar cells, and we identify possible room for improvement.