Multi-resonant Mie Resonator Arrays for Broadband Light Trapping in Ultrathin c-Si Solar Cells.

Effective photon management is critical to realize high power conversion efficiencies for thin crystalline Si (c-Si) solar cells. Standard few-100-µm-thick bulk cells achieve light trapping with macroscopic surface textures covered by thin, continuous antireflection coatings. Such sizeable textures are challenging to implement on ultrathin cells. Here, we illustrate how nanoscale Mie-resonator-arrays with a bi-modal size distribution support multiple resonances that can work in concert to achieve simultaneous antireflection and light-trapping across the broad solar spectrum. We experimentally demonstrate the effectiveness of these light-trapping antireflection coatings (LARCs) on a 2.8-µm-thick c-Si solar cell. The measured short-circuit current and corresponding power conversion efficiency are notably improved, achieving efficiencies as high as 11.2%. Measurements of the saturation current density on completed cells indicate that thermal oxides can effectively limit surface recombination. The presented design principles are applicable to a wide range of solar cells. This article is protected by copyright. All rights reserved.