Luminescent down-shifting experiment and modelling with multiple photovoltaic technologies

Luminescent down shifting (LDS) is a viable way for improving the short-wavelength response of many photovoltaic technologies, such as cadmium telluride, copper-indium-gallium-(di)selenide and multi-crystalline silicon solar cells. In this work, we compare the experimental performance of LDS layers fabricated with six organic dyes-both alone and in mixtures-and two polymers with the theoretical predictions obtained by three different approaches: ray-tracing simulations and two novel theoretical models. The first model is an analytical description of the LDS process and can reproduce the external quantum efficiency of the solar cell with LDS. The second one is based on a collection of figures of merit that address a desired property of the LDS. The three methods show an excellent agreement with the experimental results in the predicted variation of the short-circuit current (to within 0.5% in most cases) and help to understand the key factors that influence the performance of LDS, such as the optical coupling, surface roughness and scattering or edge losses. This agreement, regardless of the materials used for LDS and the underlying PV technology, not only supports the validity of the models but also suggests this theoretical formalism as a tool for designing optimised LDS layers in the future.