Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group
Journal Home About Issues in Progress Current Issue All Issues Feature Issues

Laterally assembled nanowires for ultrathin broadband solar absorbers

Kyung-Deok Song, Thomas J. Kempa, Hong-Gyu Park, and Sun-Kyung Kim

Open Access Open Access

Abstract

We studied optical resonances in laterally oriented Si nanowire arrays by conducting finite-difference time-domain simulations. Localized Fabry-Perot and whispering-gallery modes are supported within the cross section of each nanowire in the array and result in broadband light absorption. Comparison of a nanowire array with a single nanowire shows that the current density (JSC) is preserved for a range of nanowire morphologies. The JSC of a nanowire array depends on the spacing of its constituent nanowires, which indicates that both diffraction and optical antenna effects contribute to light absorption. Furthermore, a vertically stacked nanowire array exhibits significantly enhanced light absorption because of the emergence of coupled cavity-waveguide modes and the mitigation of a screening effect. With the assumption of unity internal quantum efficiency, the JSC of an 800-nm-thick cross-stacked nanowire array is 14.0 mA/cm2, which yields a ~60% enhancement compared with an equivalent bulk film absorber. These numerical results underpin a rational design strategy for ultrathin solar absorbers based on assembled nanowire cavities.

© 2014 Optical Society of America

Full Article  |  PDF Article
More Like This
Light trapping in ZnO nanowire arrays covered with an absorbing shell for solar cells

Jérôme Michallon, Davide Bucci, Alain Morand, Mauro Zanuccoli, Vincent Consonni, and Anne Kaminski-Cachopo
Opt. Express 22(S4) A1174-A1189 (2014)

Strong broadband absorption in GaAs nanocone and nanowire arrays for solar cells

Baomin Wang, Erica Stevens, and Paul W. Leu
Opt. Express 22(S2) A386-A395 (2014)

Combining 1D and 2D waveguiding in an ultrathin GaAs NW/Si tandem solar cell

Nasim Tavakoli and Esther Alarcon-Llado
Opt. Express 27(12) A909-A923 (2019)

View More...

Cited By

Optica participates in Crossref's Cited-By Linking service. Citing articles from Optica Publishing Group journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (5)
Fig. 1
Fig. 1 (A) Schematic of a core-shell p/i/n Si NW (top) and a close-packed NW array (bottom) placed on quartz substrates. (B) TE (top) and TM polarized (bottom) absorption spectra of a film, a single NW, and a close-packed NW array each with a height of 200 nm. The peak denoted by * corresponds to the whispering-gallery mode in (C). The insets in each panel show a schematic describing the polarization direction. (C) TM absorption mode profiles of the single NW (top) at λ = 450, 470, 515, and 680 nm (left to right) and the NW array (bottom) at λ = 445, 480, 515, and 695 nm (left to right).

Download Full Size | PDF

Fig. 2
Fig. 2 (A) Absorption spectra of a single NW and a NW array with circular (top) and square (bottom) cross-sectional shape. For the square NWs, a 30-nm-thick SiO2 conformal coating was introduced. The height of each NW is 200 nm. (B) Absorption spectra of a single NW and a NW array with a height of 100 nm (top) and 300 nm (bottom). The cross section of both NW structures was hexagonal.

Download Full Size | PDF

Fig. 3
Fig. 3 (A) TE (left) and TM polarized (right) absorption spectra of the NW arrays with various pitch sizes. The inset in the left panel shows a schematic of a NW array with a certain pitch size, a. (B) Snapshots of time-elapsed electric field intensity at λ = 440 nm with TE polarization (left) and λ = 445 nm with TM polarization (right) from a NW array with a = 400 nm. (C) Calculated current densities of NW arrays as a function of pitch size for TE, TM, and unpolarized (TE + TM) light.

Download Full Size | PDF

Fig. 4
Fig. 4 (A) Schematics of vertically aligned (top) and cross-stacked (bottom) NW arrays. (B) TE and TM polarized absorption spectra of double-stacked NW arrays: a cross-stacked NW array and a vertically aligned NW array. Each NW element has a height of 200 nm. All simulations are for a close-packed array. (C) TM absorption mode profiles of the peaks, indicated by “a,” “b,” “1,” and “2” in (B), corresponding to wavelengths of 580, 655, 690, and 715 nm, respectively. (D) Calculated current densities of vertically stacked NW arrays, cross-stacked NW arrays, and film structures as a function of the number of stacks, i.e., film thickness. (E) Calculated internal absorption per unit NW or unit volume for four-layered vertically aligned and cross-stacked NW arrays and an 800-nm-thick film structure. The inset shows a schematic of a four-layered NW array and a film structure.

Download Full Size | PDF

Fig. 5
Fig. 5 (A) TM polarized absorption spectra of a four-layered cross-stacked NW array and an 800-nm-thick) film structure. (B) TM absorption mode profiles of the four-layered cross-stacked NW array at wavelengths of 580, 620, 665, 685, 700, and 770 nm (left to right).

Download Full Size | PDF

Select as filters
Select Topics Cancel
Top
       
© Copyright 2024 | Optica Publishing Group. All rights reserved, including rights for text and data mining and training of artificial technologies or similar technologies.
Privacy | Terms of Use