Solution-Processed Arsenic Chalcogenides as Dopant Source and Back Contact for Efficient CdSeTe Solar Cells

Group V doping in CdSeTe device can improve power conversion efficiency (PCE) and device stability. Arsenic (As) incorporation into CdSeTe has been demonstrated via both in situ and ex situ techniques; however, optimizing the back contact for group V-doped CdSeTe devices remains a critical challenge. Here, solution-processed arsenic chalcogenides (i.e., As₂Te₃ and As₂Se₃) as dual-role materials, serving as both dopants and back-contact materials for high-efficiency CdSeTe devices, are investigated. During the formation of the back contact, a portion of the arsenic chalcogenides diffuses into the CdSeTe absorber, facilitating p-type doping. The remaining materials forms a stable back-contact layer that facilitate carrier collection and reducing recombination losses at the CdSeTe back surface. Particularly, CdSeTe device employing Te rich As₂Te₃ layer as the dopant and back-contact materials achieves a PCE of 18.34%, demonstrating the dual functionality of solution-processed arsenic chalcogenides in simultaneously doping the absorber and optimizing charge extraction. This solution based cost-effective As doping approach offers a promising pathway for advancing CdSeTe photovoltaic technology.