A self-consistent interactive model for the study of luminescence coupling in multijunction solar cells

Abstract

In this work, we propose a self-consistent interactive model based on the detailed balance approach to investigate the impact of luminescence coupling (LC) in multijunction solar cells (MJSCs). The proposed model is innovative in not using any empiric parameter input in considering the interactive nature of LC within the detailed balance framework to correlate the emissive and electrical properties of the junctions under interaction. We apply the model to radiative-limited series-connected MJSCs under different illumination conditions to demonstrate the influence of LC on the current matching condition and the impact on the power conversion efficiency (PCE) limits of such devices. As a result, we show that LC does not change the optimum bandgap energy combination leading to the highest PCE for a given operation condition but widens the span of configurations reaching high PCE, information that aids in the design of high PCE MJSC. Additionally, we analyzed some selected MJSC configurations with two to six junctions, well known from the literature to reach high PCE under different illumination conditions showing that even better performance can be achieved without either the need for changing the existent active materials or using optical thinning but using more efficient photon management concepts. Finally, we indicate MJSC configurations that can achieve high PCE for terrestrial applications under high coupling conditions, including some promises for low-cost high-efficiency photovoltaics, especially the ones involving stacks with silicon, perovskites, chalcogenides, and/or III-V materials.