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Numerical and experimental investigation of light trapping effect of nanostructured diatom frustules.

Chen X, Wang C, Baker E, Sun C - Sci Rep (2015)

Bottom Line: In contrast, diatoms, the most common type of phytoplankton found in nature, may offer a very attractive solution.In simulation, placing the diatom frustules on the surface of the light-absorption materials is found to strongly enhance the optical absorption over the visible spectrum.The absorption spectra are also measured experimentally and the results are in good agreement with numerical simulations.

View Article: PubMed Central - PubMed

Affiliation: Mechanical Engineering Department, Northwestern University, Evanston, IL 60208, USA.

ABSTRACT
Recent advances in nanophotonic light-trapping technologies offer promising solutions in developing high-efficiency thin-film solar cells. However, the cost-effective scalable manufacturing of those rationally designed nanophotonic structures remains a critical challenge. In contrast, diatoms, the most common type of phytoplankton found in nature, may offer a very attractive solution. Diatoms exhibit high solar energy harvesting efficiency due to their frustules (i.e., hard porous cell wall made of silica) possessing remarkable hierarchical micro-/nano-scaled features optimized for the photosynthetic process through millions of years of evolution. Here we report numerical and experimental studies to investigate the light-trapping characteristic of diatom frustule. Rigorous coupled wave analysis (RCWA) and finite-difference time-domain (FDTD) methods are employed to investigate the light-trapping characteristics of the diatom frustules. In simulation, placing the diatom frustules on the surface of the light-absorption materials is found to strongly enhance the optical absorption over the visible spectrum. The absorption spectra are also measured experimentally and the results are in good agreement with numerical simulations.

No MeSH data available.


(a) Optical microscopy images of Coscinodiscus sp. (b) Simplified 3D structure of the unit cell of diatom frustule based on experimental results. Thickness of the three layers: Cribellum t1 = 50 nm, Cribrum t2 = 300 nm, Internal Plate t3 = 1000 nm, (c) Left: top view of cribellum, the lattice constant p1 = 200 nm and the hole size d1 = 50 nm. Middle: top view of cribrum, the lattice constant p2 = 400 nm and the hole size d2 = 250 nm. Right: top view of internal plate, the lattice constant p3 = 2 μm and the hole size d3 = 1.3 μm.
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f1: (a) Optical microscopy images of Coscinodiscus sp. (b) Simplified 3D structure of the unit cell of diatom frustule based on experimental results. Thickness of the three layers: Cribellum t1 = 50 nm, Cribrum t2 = 300 nm, Internal Plate t3 = 1000 nm, (c) Left: top view of cribellum, the lattice constant p1 = 200 nm and the hole size d1 = 50 nm. Middle: top view of cribrum, the lattice constant p2 = 400 nm and the hole size d2 = 250 nm. Right: top view of internal plate, the lattice constant p3 = 2 μm and the hole size d3 = 1.3 μm.

Mentions: Each diatom species possesses its unique and often highly intricate frustule morphology. In previous studies, the valves of the diatom Coscinodiscus sp. have attracted much attention due to their radial symmetry with large and flat surfaces featuring well-organized multilevel pores, while other pennate diatoms are generally elongated with bilateral symmetry23. Based on the experimental study by Losic et al., the Coscinodiscus sp. frustule consists of a hierarchical structure with three constituting layers, which are named as cribellum, cribrum and the internal plate, respectively25262728. Each layer is a thin film consisting a hexagonal array of circular holes, as shown in Fig. 1. The simplified three-dimensional (3D) structure of the frustule is schematically illustrated in Fig. 1(b), in which the periodic boundary condition is chosen along the x and y direction to represent the hexagonal array of holes. The geometrical parameters are shown in Fig. 1(c). It is generally believed that the incoming sunlight undergoes strong scattering processes in the nanostructured frustule and subsequently gives rise to the light-trapping effect to enhance the photosynthesis efficiency of the natural diatoms.


Numerical and experimental investigation of light trapping effect of nanostructured diatom frustules.

Chen X, Wang C, Baker E, Sun C - Sci Rep (2015)

(a) Optical microscopy images of Coscinodiscus sp. (b) Simplified 3D structure of the unit cell of diatom frustule based on experimental results. Thickness of the three layers: Cribellum t1 = 50 nm, Cribrum t2 = 300 nm, Internal Plate t3 = 1000 nm, (c) Left: top view of cribellum, the lattice constant p1 = 200 nm and the hole size d1 = 50 nm. Middle: top view of cribrum, the lattice constant p2 = 400 nm and the hole size d2 = 250 nm. Right: top view of internal plate, the lattice constant p3 = 2 μm and the hole size d3 = 1.3 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4496668&req=5

f1: (a) Optical microscopy images of Coscinodiscus sp. (b) Simplified 3D structure of the unit cell of diatom frustule based on experimental results. Thickness of the three layers: Cribellum t1 = 50 nm, Cribrum t2 = 300 nm, Internal Plate t3 = 1000 nm, (c) Left: top view of cribellum, the lattice constant p1 = 200 nm and the hole size d1 = 50 nm. Middle: top view of cribrum, the lattice constant p2 = 400 nm and the hole size d2 = 250 nm. Right: top view of internal plate, the lattice constant p3 = 2 μm and the hole size d3 = 1.3 μm.
Mentions: Each diatom species possesses its unique and often highly intricate frustule morphology. In previous studies, the valves of the diatom Coscinodiscus sp. have attracted much attention due to their radial symmetry with large and flat surfaces featuring well-organized multilevel pores, while other pennate diatoms are generally elongated with bilateral symmetry23. Based on the experimental study by Losic et al., the Coscinodiscus sp. frustule consists of a hierarchical structure with three constituting layers, which are named as cribellum, cribrum and the internal plate, respectively25262728. Each layer is a thin film consisting a hexagonal array of circular holes, as shown in Fig. 1. The simplified three-dimensional (3D) structure of the frustule is schematically illustrated in Fig. 1(b), in which the periodic boundary condition is chosen along the x and y direction to represent the hexagonal array of holes. The geometrical parameters are shown in Fig. 1(c). It is generally believed that the incoming sunlight undergoes strong scattering processes in the nanostructured frustule and subsequently gives rise to the light-trapping effect to enhance the photosynthesis efficiency of the natural diatoms.

Bottom Line: In contrast, diatoms, the most common type of phytoplankton found in nature, may offer a very attractive solution.In simulation, placing the diatom frustules on the surface of the light-absorption materials is found to strongly enhance the optical absorption over the visible spectrum.The absorption spectra are also measured experimentally and the results are in good agreement with numerical simulations.

View Article: PubMed Central - PubMed

Affiliation: Mechanical Engineering Department, Northwestern University, Evanston, IL 60208, USA.

ABSTRACT
Recent advances in nanophotonic light-trapping technologies offer promising solutions in developing high-efficiency thin-film solar cells. However, the cost-effective scalable manufacturing of those rationally designed nanophotonic structures remains a critical challenge. In contrast, diatoms, the most common type of phytoplankton found in nature, may offer a very attractive solution. Diatoms exhibit high solar energy harvesting efficiency due to their frustules (i.e., hard porous cell wall made of silica) possessing remarkable hierarchical micro-/nano-scaled features optimized for the photosynthetic process through millions of years of evolution. Here we report numerical and experimental studies to investigate the light-trapping characteristic of diatom frustule. Rigorous coupled wave analysis (RCWA) and finite-difference time-domain (FDTD) methods are employed to investigate the light-trapping characteristics of the diatom frustules. In simulation, placing the diatom frustules on the surface of the light-absorption materials is found to strongly enhance the optical absorption over the visible spectrum. The absorption spectra are also measured experimentally and the results are in good agreement with numerical simulations.

No MeSH data available.