Coupled modelling approach for optimization of bifacial silicon heterojunction solar cells with multi-scale interface textures

For advanced optical analysis and optimization of solar cell structures with multi-scale interface textures, we applied a coupled modelling approach (CMA), where we couple the rigorous coupled wave analysis method with ray tracing and transfer matrix method. Coupling of the methods enables accurate optical analysis of solar cells made of thin coherent and thick incoherent layers and includes combinations of nano-and micro-scale textures at various positions in the structure. The approach is experimentally validated on standalone single-and both-side textured crystalline silicon wafers, as well as on complete silicon heterojunction (Si HJ) solar cell structures. Using CMA, fully encapsulated bifacial Si HJ solar cells are optically simulated first by applying single-and both-side illumination, and the effects of introducing nano inverted pyramids and random micro-pyramids at front and/or rear interfaces are analyzed. Secondly, an external light management foil with a three-sided pyramidal micro-texture is applied in simulations to the front and/or rear encapsulation glass, and the related improvements are quantified. For the optimal combination of internal textures in the analyzed structure (random micro-pyramids at the front and nano inverted pyramids at the back) and the use of the light management foil on both sides of the device, a 5.6% gain in the short-circuit current is predicted, compared to the reference case with no light management foil and with random micro-pyramids applied to the front and rear internal interfaces. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement