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. Copyright © 2014 John Wiley & Sons, Ltd.

Predicting lithium-ion battery degradation is worth billions to the global automotive, aviation and energy storage industries, to improve performance and safety and reduce warranty liabilities. However, very few published models...

A comprehensive assessment of the nature of the distribution of sub band-gap energy states in bulk GaAsBi is presented using power and temperature dependent photoluminescence spectroscopy. The observation of a characteristic red-blue-red shift in the peak luminescence energy indicates the presence of short-range alloy disorder in the material. A decrease in the carrier localisation energy demonstrates the strong excitation power dependence of localised state behaviour and is attributed to the filling of energy states furthest from the valence band edge. Analysis of the photoluminescence lineshape at low temperature presents strong evidence for a Gaussian distribution of localised states that extends from the valence band edge. Furthermore, a rate model is employed to understand the non-uniform thermal quenching of the photoluminescence and indicates the presence of two Gaussian-like distributions making up the density of localised states. These components are attributed to the presence of microscopic fluctuations in Bi content, due to short-range alloy disorder across the GaAsBi layer, and the formation of Bi related point defects, resulting from low temperature growth.

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