Overcoming the poor short wavelength spectral response of CdS/CdTe photovoltaic modules via luminescence down-shifting: Ray-tracing simulations

The short-wavelength response of cadmium sulfide/cadmium telluride (CdS/CdTe) photovoltaic (PV) modules can be improved by the application of a luminescent downshifting (LDS) layer to the PV module. The LDS layer contains a mixture of fluorescent organic dyes that are able to absorb short-wavelength light of λ < 540 nm, nm, for which the PV module exhibited low external quantum efficiency (EQE), and re-emit it at a longer wavelength (λ > 540 nm), where the solar cell EQE is high. Raytracing simulations indicate that a mixed LDS layer containing three dyes could lead to an increase in the short-circuit current density from J_sc = 19.8 mA/cm ² to J_sc = 22.9 mA/cm² for a CdS/CdTe PV module. This corresponds to an increase in conversion efficiency from 9.6% to 11.2%. This indicates that a relative increase in the performance of a production CdS/CdTe PV module of nearly 17% can be expected via the application of LDS layers, possibly without any making any alterations to the solar cell itself.