Preprint article · Journal article
Strongly enhanced upconversion in trivalent erbium ions by tailored gold nanostructures: Toward high-efficient silicon-based photovoltaics
Upconversion of sub-band-gap photons constitutes a promising way for improving the efficiency of silicon-based solar cells beyond the Shockley-Queisser limit. 1500 nm to 980 nm upconversion by trivalent erbium ions is well-suited for this purpose, but the small absorption cross section hinders real-world applications.
We employ tailored gold nanostructures to vastly improve the upconversion efficiency in erbium-doped TiO thin films. The nanostructures are found using topology optimization and parameter optimization and fabricated by electron beam lithography. In qualitative agreement with a theoretical model, the samples show substantial electric-field enhancements inside the upconverting films for excitation at 1500 nm for both s- and p-polarization under a wide range of incidence angles and excitation intensities.
An unprecedented upconversion enhancement of 913 ± 51 is observed at 1.7 W cm−2. We derive a semi-empirical expression for the photonically enhanced upconversion efficiency, valid for all excitation intensities. This allows us to determine the upconversion properties needed to achieve significant improvements in real-world solar-cell devices through photonic-enhanced upconversion.
Language: | English |
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Year: | 2020 |
Pages: | 110406 |
ISSN: | 18793398 and 09270248 |
Types: | Preprint article and Journal article |
DOI: | 10.1016/j.solmat.2020.110406 |
ORCIDs: | 0000-0003-0221-1461 , 0000-0002-9813-8360 , Christiansen, Rasmus E. and Sigmund, Ole |
High-efficient photovoltaics Photonic enhancement Topology optimization Upconversion of sub-band gap photons