Effects of MgF₂ anti-reflection coating on optical losses in metal halide perovskite solar cells

Abstract

The importance of light management for perovskite solar cells (PSCs) has recently been emphasized because their power conversion efficiency approaches their theoretical thermodynamic limits. Among optical strategies, anti-reflection (AR) coating is the most widely used method to reduce reflectance loss and thus increase light-harvesting efficiency. Monolayer MgF2 is a well-known AR material because of its optimal refractive index, simple fabrication process, and physical and chemical durabilities. Nevertheless, quantitative estimates of the improvement achieved by the MgF2 AR layer are lacking. In this study, we conducted theoretical and experimental evaluations to assess the AR effect of MgF2 on the performance of formamidinium lead-triiodide PSCs. A sinusoidal tendency to enhance the short-circuit current density (JSC) was observed depending on the thickness, which was attributed to the interference of the incident light. A transfer matrix method-based simulation was conducted to calculate the optical losses, demonstrating the critical impact of reflectance loss on the JSC improvement. The predicted JSCs values, depending on the perovskite thickness and the incident angle, are also presented. The combined use of experimental and theoretical approaches offers notable advantages, including accurate interpretation of photocurrent generation, detailed optical analysis of the experimental results, and device performance predictions under unexplored conditions.

A Rational Approach to Improve the Overall Performances of Semitransparent Perovskite Solar Cells by Electrode Optical Management

“…Since our strategy is not dependent on the active layer used, a further increment of such performances could be achieved by mixing different halide-based perovskites or organic materials to tune the absorption spectrum of the active layer . Moreover, we emphasize that our approach is universal as it can be extended to several DMD materials and optoelectronic device applications, including infrared perovskite solar cells and tandem architectures. − Antireflection coatings such as MgF 2 are widely used in photovoltaic devices . By contrast, the DMD architecture offers the advantage to conduct carriers, allowing one also to obtain bifacial semitransparent solar cells with high reproducible results.…”