Routes for Light Management in Monolithic Perovskite/Silicon Tandem Solar Cells

TL;DR

The paper addresses light management in monolithic perovskite/silicon tandem solar cells, noting that full texturing can improve optics but induce large electrical losses when perovskite texturing is involved. Using optical simulations with Rayflare and a two-diode electrical model, it decouples the roles of front and rear textures, finding that front texturing primarily enhances silicon absorption in the $700$–$980$ nm range and rear texturing boosts absorption above $1000$ nm, while perovskite texturing is not essential for optical gains. Guided by these insights, it proposes a planar-perovskite tandem architecture with a carefully optimized front ARC texture and an unchanged rear silicon texture, achieving optical performance comparable to fully textured devices and predicting a PCE around 32.15% for the proposal vs 32.94% for the fully textured case under current matching; importantly, with a modest Voc penalty as low as 50 mV, the planar design can surpass the fully textured configuration. Overall, the work suggests a scalable route to high-efficiency PSTSCs by separating optical management from perovskite surface texturing, potentially reducing electrical losses and fabrication complexity.

Abstract

Fully-textured perovskite/silicon tandem solar cells have emerged as promising candidates for next-generation photovoltaics. The optical functions of full texturing, however, are not yet fully understood. A key challenge is the requirement for perovskite layer texturing, which often leads to increased electrical losses. Here, we elucidate the distinct optical roles of front and rear textures in tandem configurations using optical simulations and use these insights to propose a new architecture that eliminates the need for perovskite surface texturing. We demonstrate that our proposed structure achieves optical results comparable to those of fully-textured devices, while its planar perovskite layer has the potential to reduce electrical losses. The high optical performance also results in higher efficiency if a texture-induced voltage loss as low as 50 mV is assumed, which is about six times lower than the loss of fully-textured devices, thus enabling higher efficiencies within a simplified design. Our results show that perovskite texturing is not essential for optimal light management, thus opening the way to combine efficient light management with high electrical performance.

Figures (6)

• Figure 1: Tandem cell architectures used for optical benchmarking: (a) fully-textured, state-of-the-art configuration; (b) planar reference.
• Figure 2: Light management effects in a fully-textured PSTSC architecture: (a) device stacks considered for the optical characterizations; (b) short-circuit current density ($J_\mathrm{sc}$) of the perovskite subcell for planar (stack A) and fully-textured (stack B) structures; inset: front-surface reflectance from stacks A and B; (c) spectral absorptance in the perovskite and silicon layers for stacks A--D.
• Figure 3: Proposed structure. The top inset highlights the geometry of the anti-reflective front-side texture optimized here. The bottom inset shows the state-of-the-art pyramidal texturing used at the rear silicon interface, which remains unaltered in comparison to all previous textured stacks.
• Figure 4: Short-circuit current density ($J_{\mathrm{sc}}$) as a function of the ARC pyramid inclination angle. The optimal angle of 44$^\circ$ maximizes both the silicon and perovskite currents.
• Figure 5: Spectral absorptance in the perovskite and silicon subcells for the proposed and fully-textured architectures. The proposed structure maintains comparable optical performance while simplifying the top interface.