Photoluminescence and carrier dynamics of antimony-doped CdTe and graded CdSeTe

Group V doping is a key strategy to achieve the equilibrium hole concentrations in cadmium telluride (CdTe) photovoltaics required to exceed 25% power conversion efficiency. While arsenic-doped devices have surpassed 23% efficiency, low dopant activation and dopant-related defects continue to limit open-circuit voltage (V OC ). Here, we report on antimony (Sb) incorporation during vapor transport deposition of CdTe and graded CdSeTe absorbers and its impact on photoluminescence and carrier dynamics. Sb incorporation was controlled by the dopant source temperature during deposition, followed by CdCl 2 treatment; and graded CdSeTe with the highest dopant source temperature was also subjected to varied CdCl 2 treatments. Sb concentrations up to ∼3x10 17 cm −3 were achieved. Steady-state photoluminescence spectra and optical pump – terahertz probe decays were largely unchanged across a ten-fold increase in Sb concentration in both CdTe and graded CdSeTe, indicating that moderate Sb incorporation does not intrinsically degrade radiative properties or carrier dynamics. In contrast, high Sb source temperature introduced new deep defect-related emission in CdTe, broadened sub-bandgap emission in graded CdSeTe, and showed substantially faster decays, consistent with increased carrier trapping or recombination associated with processing-induced defects. An alternative CdCl 2 heat treatment increased hole concentrations from ∼1x10 15 to 3x10 16 cm −3 and increased V OC but at the cost of increased trapping and reduced fill factor. These results highlight the critical interplay between dopant incorporation and post-deposition processing in governing defect chemistry and device-relevant optoelectronic properties in Sb-doped CdTe and CdSeTe absorbers.