Upper Bounds on Broadband Absorption and Application to Solar Cells
Abstract
We address the question of the optimal broadband absorption of waves in an open dissipative system and its key implications for solar cells. We develop a general framework for absorption induced by multiple overlapping resonances, based on quasinormal modes and radiative and nonradiative decay rates. We demonstrate that the upper bounds on broadband absorption in a slab of thickness d take the simple form A = 1 − exp ( − F α d ) , where α is the absorption coefficient and F is the path enhancement factor. We apply these results to sunlight absorption in photovoltaics and answer the long-standing debate on the best light-trapping strategy in solar cells. For angle-independent absorption enhanced by scattering, we derive the isotropic upper bound F = 4 n 2 (where n is the refractive index), extending the well-known Lambertian (or Yablonovitch) limit beyond the ray-optics and weak-absorption regimes. For angle-restricted illumination, we show that F can be further increased up to 8 π n 2 / 3 using multiresonant absorption induced by periodical patterning. These results have a general scope in the field of wave physics and open new opportunities to maximize absorption, detection, and attenuation of electromagnetic or mechanical waves in ultrathin devices.
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BibTeX
@article{collin2026upper,
title = {{Upper Bounds on Broadband Absorption and Application to Solar Cells}},
author = {Stéphane Collin and Maxime Giteau},
journal = {PRX Energy},
year = {2026},
month = may,
doi = {10.1103/1tzg-hgqx},
url = {https://hal.science/hal-05800696v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Upper Bounds on Broadband Absorption and Application to Solar Cells
AU - Stéphane Collin
AU - Maxime Giteau
PY - 2026
DA - 2026/05/26
JO - PRX Energy
DO - 10.1103/1tzg-hgqx
UR - https://hal.science/hal-05800696v1
AB - We address the question of the optimal broadband absorption of waves in an open dissipative system and its key implications for solar cells. We develop a general framework for absorption induced by multiple overlapping resonances, based on quasinormal modes and radiative and nonradiative decay rates. We demonstrate that the upper bounds on broadband absorption in a slab of thickness d take the simple form A = 1 − exp ( − F α d ) , where α is the absorption coefficient and F is the path enhancement factor. We apply these results to sunlight absorption in photovoltaics and answer the long-standing debate on the best light-trapping strategy in solar cells. For angle-independent absorption enhanced by scattering, we derive the isotropic upper bound F = 4 n 2 (where n is the refractive index), extending the well-known Lambertian (or Yablonovitch) limit beyond the ray-optics and weak-absorption regimes. For angle-restricted illumination, we show that F can be further increased up to 8 π n 2 / 3 using multiresonant absorption induced by periodical patterning. These results have a general scope in the field of wave physics and open new opportunities to maximize absorption, detection, and attenuation of electromagnetic or mechanical waves in ultrathin devices.
SN - 2768-5608
ER -