Efficient black silicon solar cell with a density-graded nanoporous surface: Optical properties, performance limitations, and design rules

TLDR

We investigate the optical effects and performance limits of 16.8 % efficient black silicon solar cells and propose universal design rules for high‑efficiency cells based on density‑graded surfaces. The cells feature density‑graded nanoporous surface layers fabricated by a one‑step nanoparticle‑catalyzed etch, reflecting less than 3 % of the solar spectrum without conventional antireflection coatings. Recombination within the nanoporous layer limits short‑wavelength response, and the optimal layer depth balances reflectance reduction against this recombination loss.

Abstract

We study optical effects and factors limiting performance of our confirmed 16.8% efficiency “black silicon” solar cells. The cells incorporate density-graded nanoporous surface layers made by a one-step nanoparticle-catalyzed etch and reflect less than 3% of the solar spectrum, with no conventional antireflection coating. The cells are limited by recombination in the nanoporous layer which decreases short-wavelength spectral response. The optimum density-graded layer depth is then a compromise between reflectance reduction and recombination loss. Finally, we propose universal design rules for high-efficiency solar cells based on density-graded surfaces.