Advanced Optical Modelling of Micro-Textured Solution-Processed Solar Cells with Consideration of Small-Area Effects
Benjamin Lipovsek1, Marko Jost1, Andrej Campa1, Fei Guo2, Christoph J Brabec2, Karen Forberich2, Janez Krc1, Marko Topic1
1University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, Slovenia
/2Friedrich-Alexander-Univeristät Erlangen-Nürnberg, Erlangen, Germany

Solution-processed organic and perovskite solar cells show great potential for future evolution of the photovoltaic industry. However, research oriented towards improving both the electrical and optical properties of these devices is needed for further increasing their conversion efficiency.

In the scope of optical investigation, advanced optical modelling techniques based on the combination of different numerical methods are required for efficient design and optimization of complex solar cells structures that can include thin and thick layers, nano- and micro-scale interface textures, etc. In this contribution, we discuss the applicability of such modelling techniques for detailed optical investigation of solution-processed solar cells enhanced with a micro-textured light management foil at the front side.

First, using the optical simulator CROWM calibrated with realistic optical properties of the materials, we investigate the potential of ligth-management foils and identify their most important light management mechanisms. Among these, the prevention of light escaping from the cells at the front side is revealed as the dominant one. Simulations show that the foils can dramatically reduce the total reflection losses and substantially improve the short-circuit current density of the investigated solar cells.

Next, we focus on the effects caused by the limited area of typical lab-scale prototype solar cells. We demonstrate that measurements of small-area cells are susceptible to a significant amount of optical losses that could lead to false interpretation of the results. Advanced optical modelling is used to identify the origins of these losses and quantify the extent of their influence on the measured characteristics. Finally, we also investigate how these losses depend on the geometry parameters of both the solar cells (area, thickness, texture profile) as well as the measurement system (beam size). We indicate the minimum geometry requirements of the fabricated solution-processed cells that would enable reliable acquisition of measured data.

Area: Sub-Area 6.2: Organic and Hybrid Solar Cells