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Light Trapping Enhancement in a Thin Film with 2D Conformal Periodic Hexagonal Arrays.

Yang X, Zhou S, Wang D, He J, Zhou J, Li X, Gao P, Ye J - Nanoscale Res Lett (2015)

Bottom Line: Compared with the planar reference, the double-sided conformal periodic structures with all feature periodicities of sub-wavelength (300 nm), mid-wavelength (640 nm), and infrared wavelength (2300 nm) show significant broadband absorption enhancements under wide angles.The films with an optimum periodicity of 300 nm exhibit outstanding antireflection and excellent trade-off between light scattering performance and parasitic absorption loss.The average absorption of the optimum structure with a thickness of 160 nm is 64.8 %, which is much larger than the planar counterpart of 38.5 %.

View Article: PubMed Central - PubMed

Affiliation: Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China, yangx@nimte.ac.cn.

ABSTRACT
Applying a periodic light trapping array is an effective method to improve the optical properties in thin-film solar cells. In this work, we experimentally and theoretically investigate the light trapping properties of two-dimensional periodic hexagonal arrays in the framework of a conformal amorphous silicon film. Compared with the planar reference, the double-sided conformal periodic structures with all feature periodicities of sub-wavelength (300 nm), mid-wavelength (640 nm), and infrared wavelength (2300 nm) show significant broadband absorption enhancements under wide angles. The films with an optimum periodicity of 300 nm exhibit outstanding antireflection and excellent trade-off between light scattering performance and parasitic absorption loss. The average absorption of the optimum structure with a thickness of 160 nm is 64.8 %, which is much larger than the planar counterpart of 38.5 %. The methodology applied in this work can be generalized to rational design of other types of high-performance thin-film photovoltaic devices based on a broad range of materials.

No MeSH data available.


Absorption spectra. a Absorption spectra of 300-nm periodic samples with a Ag layer of 200-, 300-, and 400-nm thicknesses; the planar film with the Ag layer of 200-nm thickness is used as a reference, and the thickness of the a-Si layer in all four samples is 160 nm. b Absorption spectra of 300-nm periodic samples with an a-Si layer of 120-, 200-, and 280-nm thicknesses. c The absorption spectra of the three planar samples are used as the references relative to the periodic ones in b; the thickness of Ag in b and c is fixed at 200 nm
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Fig5: Absorption spectra. a Absorption spectra of 300-nm periodic samples with a Ag layer of 200-, 300-, and 400-nm thicknesses; the planar film with the Ag layer of 200-nm thickness is used as a reference, and the thickness of the a-Si layer in all four samples is 160 nm. b Absorption spectra of 300-nm periodic samples with an a-Si layer of 120-, 200-, and 280-nm thicknesses. c The absorption spectra of the three planar samples are used as the references relative to the periodic ones in b; the thickness of Ag in b and c is fixed at 200 nm

Mentions: To further explore the benefits brought by the conformal hexagonal configuration, the absorption properties of the structures with different thicknesses of the Ag and a-Si films are investigated in detail. All these studies are based on the structures with P = 300 nm, which leads to the highest light trapping performance according to our experiments. It is worth noting that the surface morphology flattens out when the deposited films (Ag and a-Si) are getting thicker. Figure 5a shows the absorption spectra of periodic samples with a top a-Si layer of 160 nm and a bottom Ag layer of 200, 300, and 400 nm, respectively. The absorptions of all three samples in the short wavelength ranges (300–550 nm) are similar, and they start to be different at a longer wavelength range of λ > 550 nm mainly due to the different surface topographies induced by the different thicknesses of the Ag layer. It is worth noting that the absorption peaks are redshifted with increasing thickness of the Ag film. The top surface topography would change the incident angles of the light that reaches the bottom and affect light absorption, although the exact effect on light confinement at long wavelength is difficult to predict. Figure 5b depicts the absorption spectra of samples with a Ag layer of 200 nm but with an a-Si film of various thicknesses. With the increasing thickness of the a-Si film, the average absorption at the wavelength range of 300 nm < λ < 600 nm increases and the absorption peaks arising from the FP cavity modes are redshifted. At the wavelength range of λ > 600 nm, the light trapping of the periodic structures is distinctively superior to that of the planar reference as shown in Fig. 5c. Compared with the planar one, the average absorption of the optimum structure with an a-Si layer of 280-nm thickness and a Ag layer of 200-nm thickness is boosted by 71.6 %, from 45.1 to 77.4 % over the whole wavelength due to the presence of the periodic configuration.Fig. 5


Light Trapping Enhancement in a Thin Film with 2D Conformal Periodic Hexagonal Arrays.

Yang X, Zhou S, Wang D, He J, Zhou J, Li X, Gao P, Ye J - Nanoscale Res Lett (2015)

Absorption spectra. a Absorption spectra of 300-nm periodic samples with a Ag layer of 200-, 300-, and 400-nm thicknesses; the planar film with the Ag layer of 200-nm thickness is used as a reference, and the thickness of the a-Si layer in all four samples is 160 nm. b Absorption spectra of 300-nm periodic samples with an a-Si layer of 120-, 200-, and 280-nm thicknesses. c The absorption spectra of the three planar samples are used as the references relative to the periodic ones in b; the thickness of Ag in b and c is fixed at 200 nm
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4495099&req=5

Fig5: Absorption spectra. a Absorption spectra of 300-nm periodic samples with a Ag layer of 200-, 300-, and 400-nm thicknesses; the planar film with the Ag layer of 200-nm thickness is used as a reference, and the thickness of the a-Si layer in all four samples is 160 nm. b Absorption spectra of 300-nm periodic samples with an a-Si layer of 120-, 200-, and 280-nm thicknesses. c The absorption spectra of the three planar samples are used as the references relative to the periodic ones in b; the thickness of Ag in b and c is fixed at 200 nm
Mentions: To further explore the benefits brought by the conformal hexagonal configuration, the absorption properties of the structures with different thicknesses of the Ag and a-Si films are investigated in detail. All these studies are based on the structures with P = 300 nm, which leads to the highest light trapping performance according to our experiments. It is worth noting that the surface morphology flattens out when the deposited films (Ag and a-Si) are getting thicker. Figure 5a shows the absorption spectra of periodic samples with a top a-Si layer of 160 nm and a bottom Ag layer of 200, 300, and 400 nm, respectively. The absorptions of all three samples in the short wavelength ranges (300–550 nm) are similar, and they start to be different at a longer wavelength range of λ > 550 nm mainly due to the different surface topographies induced by the different thicknesses of the Ag layer. It is worth noting that the absorption peaks are redshifted with increasing thickness of the Ag film. The top surface topography would change the incident angles of the light that reaches the bottom and affect light absorption, although the exact effect on light confinement at long wavelength is difficult to predict. Figure 5b depicts the absorption spectra of samples with a Ag layer of 200 nm but with an a-Si film of various thicknesses. With the increasing thickness of the a-Si film, the average absorption at the wavelength range of 300 nm < λ < 600 nm increases and the absorption peaks arising from the FP cavity modes are redshifted. At the wavelength range of λ > 600 nm, the light trapping of the periodic structures is distinctively superior to that of the planar reference as shown in Fig. 5c. Compared with the planar one, the average absorption of the optimum structure with an a-Si layer of 280-nm thickness and a Ag layer of 200-nm thickness is boosted by 71.6 %, from 45.1 to 77.4 % over the whole wavelength due to the presence of the periodic configuration.Fig. 5

Bottom Line: Compared with the planar reference, the double-sided conformal periodic structures with all feature periodicities of sub-wavelength (300 nm), mid-wavelength (640 nm), and infrared wavelength (2300 nm) show significant broadband absorption enhancements under wide angles.The films with an optimum periodicity of 300 nm exhibit outstanding antireflection and excellent trade-off between light scattering performance and parasitic absorption loss.The average absorption of the optimum structure with a thickness of 160 nm is 64.8 %, which is much larger than the planar counterpart of 38.5 %.

View Article: PubMed Central - PubMed

Affiliation: Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China, yangx@nimte.ac.cn.

ABSTRACT
Applying a periodic light trapping array is an effective method to improve the optical properties in thin-film solar cells. In this work, we experimentally and theoretically investigate the light trapping properties of two-dimensional periodic hexagonal arrays in the framework of a conformal amorphous silicon film. Compared with the planar reference, the double-sided conformal periodic structures with all feature periodicities of sub-wavelength (300 nm), mid-wavelength (640 nm), and infrared wavelength (2300 nm) show significant broadband absorption enhancements under wide angles. The films with an optimum periodicity of 300 nm exhibit outstanding antireflection and excellent trade-off between light scattering performance and parasitic absorption loss. The average absorption of the optimum structure with a thickness of 160 nm is 64.8 %, which is much larger than the planar counterpart of 38.5 %. The methodology applied in this work can be generalized to rational design of other types of high-performance thin-film photovoltaic devices based on a broad range of materials.

No MeSH data available.