Disordered Photonic Crystal Slabs for Thin-Film Photovoltaics

Inquiry@Queen's Undergraduate Research Conference Proceedings ◽

10.24908/iqurcp.9966 ◽

2018 ◽

Author(s):

Chelsea Carlson

Keyword(s):

Thin Film ◽

Photonic Crystal ◽

Near Infrared ◽

Crystalline Silicon ◽

Solar Spectrum ◽

Silicon Layer ◽

Physical Parameters ◽

Photonic Crystal Slabs ◽

Optical Applications ◽

Conversion Efficiencies

Photonic crystal nanostructures are the foundation for many optical applications such as nanochip waveguides, optical fibres, and high-Q nanocavities. Recently, researchers have begun to explore the use of photonic crystal slabs to increase the overall absorption of sunlight in thin-film solar photovoltaic (PV) cells. Currently, amorphous silicon (a-Si:H) thin-film technologies can only achieve efficiencies of up to 16% in laboratories and less than 10% in manufactured commercial products. The difficulty in improving these efficiencies arises from the inherent band gap properties of the crystalline silicon layer: the natural photonic bandgap in the near infrared (IR) region of light prohibits almost a third of the entire available solar spectrum from being absorbed. Some of this loss can be salvaged by increasing the thickness of the silicon layer, but this drives the price of the cell up and has very limited potential. However, using photonic crystal nanostructures in the active layer of the cell can decrease the reflection of light at the surface and increase the photon path within the film, enhancing the collection and conversion efficiencies over a broad spectrum. The absorption can be further increased by introducing pseudo-disorder within the structures. The purpose of this study was to explore the physical parameters of this disorder and quantitatively optimize absorption.

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Air-bridged photonic crystal slabs at visible and near-infrared wavelengths

Physical Review B ◽

10.1103/physrevb.73.115126 ◽

2006 ◽

Vol 73 (11) ◽

Cited By ~ 103

Author(s):

K. B. Crozier ◽

Virginie Lousse ◽

Onur Kilic ◽

Sora Kim ◽

Shanhui Fan ◽

...

Keyword(s):

Photonic Crystal ◽

Near Infrared ◽

Photonic Crystal Slabs ◽

Infrared Wavelengths

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DETERMINATION OF THE COMPLEX REFRACTIVE INDEX OF POROUS SILICON LAYERS ON CRYSTALLINE SILICON SUBSTRATES

International Journal of Modern Physics B ◽

10.1142/s0217979210054932 ◽

2010 ◽

Vol 24 (24) ◽

pp. 4835-4850 ◽

Cited By ~ 9

Author(s):

M. C. ARENAS ◽

HAILIN HU ◽

R. NAVA ◽

J. A. DEL RÍO

Keyword(s):

Thin Film ◽

Refractive Index ◽

Porous Silicon ◽

Extinction Coefficient ◽

Near Infrared ◽

Crystalline Silicon ◽

Complex Refractive Index ◽

Si Substrate ◽

Free Standing ◽

Analytical Relations

In this work, we show an algorithm to calculate the complex refractive index of porous silicon (PS) on its crystalline silicon (c-Si) substrate in UV-NIR range by means of the reflectance spectra only. The algorithm is based on the analytical relations established by Heavens to obtain both complex refractive index and thickness of an absorbing thin film on an absorbing substrate. Based on this model, some simplification is introduced at different wavelengths. We start with the NIR range (1000–2500 nm), where the c-Si substrate has a low extinction coefficient. Then, we continue with the near infrared to the optical range (300–1000 nm), where PS has a strong extinction coefficient and dispersion. The calculated n and k values are in agreement with those reported in the literature obtained from separated measurements of a free standing PS film. We consider that the algorithm can be applied to any thin film on a substrate with similar optical properties.

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Design and fabrication of rod-type two-dimensional photonic crystal slabs with large high-order bandgaps in near-infrared wavelengths

Optics Letters ◽

10.1364/ol.37.001424 ◽

2012 ◽

Vol 37 (9) ◽

pp. 1424 ◽

Cited By ~ 10

Author(s):

Liyong Jiang ◽

Wei Jia ◽

Gaige Zheng ◽

Xiangyin Li

Keyword(s):

Photonic Crystal ◽

Near Infrared ◽

High Order ◽

Two Dimensional ◽

Dimensional Photonic Crystal ◽

Photonic Crystal Slabs ◽

Infrared Wavelengths ◽

Two Dimensional Photonic Crystal

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Subwavelength Imaging Characteristics of the Near-Infrared Silicon-Based Metallic Photonic Crystal Slabs

Acta Optica Sinica ◽

10.3788/aos201333.0123003 ◽

2013 ◽

Vol 33 (1) ◽

pp. 0123003

Author(s):

陈胥冲 Chen Xuchong ◽

冯帅 Feng Shuai ◽

张贝贝 Zhang Beibei ◽

李超 Li Chao ◽

王义全 Wang Yiquan

Keyword(s):

Photonic Crystal ◽

Near Infrared ◽

Subwavelength Imaging ◽

Photonic Crystal Slabs ◽

Imaging Characteristics ◽

Silicon Based ◽

Metallic Photonic Crystal

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Realization of Significant Absorption Enhancement in Thin Film Silicon Solar Cells with Textured Photonic Crystal Backside Reflector

MRS Proceedings ◽

10.1557/proc-1123-1123-p02-01 ◽

2008 ◽

Vol 1123 ◽

Author(s):

Lirong Zeng ◽

Peter Bermel ◽

Yasha Yi ◽

Bernard A. Alamariu ◽

Kurt A. Broderick ◽

...

Keyword(s):

Thin Film ◽

Solar Cells ◽

Photonic Crystal ◽

Near Infrared ◽

Light Trapping ◽

Short Circuit ◽

Large Angle ◽

Bragg Reflector ◽

Absorption Enhancement ◽

Si Solar Cells

AbstractThe major factor limiting the efficiencies of thin film Si solar cells is their weak absorption of red and near-infrared photons due to short optical path length and indirect bandgap. Powerful light trapping is essential to confine light inside the cell for sufficient absorption. Here we report the first experimental application of a new light trapping scheme, the textured photonic crystal (TPC) backside reflector, to monocrystalline thin film Si solar cells. TPC combines a onedimensional photonic crystal, i.e., a distributed Bragg reflector (DBR), with a reflection grating. The near unity reflectivity of DBR in a wide omnidirectional bandgap and the large angle diffraction by the grating ensures a strong enhancement in the absorption of red and near-infrared photons, leading to significant improvements in cell efficiencies. Measured short circuit current density Jsc was increased by 19% for 5 μm thick cells, and 11% for 20 μm thick cells, compared to theoretical predictions of 28% and 14%, respectively.

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INFLUENCE OF ANNEALING TEMPERATURE ON SOME OPTICAL AND STRUCTURAL PROPERTIES OF Cu2ZnSnS4 DEPOSITED BY CZT CO-ELECTRODEPOSITION COUPLED WITH CHEMICAL BATH TECHNIQUE

Surface Review and Letters ◽

10.1142/s0218625x18500750 ◽

2018 ◽

Vol 25 (03) ◽

pp. 1850075

Author(s):

OBILA JORIM OKOTH ◽

DINFA LUKA DOMTAU ◽

MUKABI MARINA ◽

ONYATTA JOHN ◽

OGACHO ALEX AWUOR

Keyword(s):

Thin Film ◽

Near Infrared ◽

Low Cost ◽

Solar Spectrum ◽

Electrical Characterization ◽

Czts Film ◽

Infrared Range ◽

Earth Abundant ◽

Czts Thin Films ◽

Material Scarcity

Copper indium gallium selenide (CIGS) is currently most efficient thin film solar technology in use but it is faced with problems of material scarcity and toxicity. An alternative earth abundant and non-toxic materials consisting of Cu2ZnSnS4 (CZTS) have been investigated as a replacement for CIGS. In this work, CZTS thin films deposited by low cost co-electrodeposition, at a potential of [Formula: see text]1.2[Formula: see text]V, coupled with chemical bath techniques at room temperature and then annealed under sulphur rich atmosphere were investigated. CZTS thin film quality determination was carried out using Raman spectroscopy which confirmed formation of quality CZTS film, main Raman peaks at 288[Formula: see text]cm[Formula: see text] and 338[Formula: see text]cm[Formula: see text] were observed. Electrical characterization was carried out using four-point probe instrument and the resistivity was in the order of [Formula: see text]-cm. The optical characterization was done using UV-VIS-NIR spectrophotometer. The bandgaps of the annealed CZTS film ranged from 1.45 to 1.94[Formula: see text]eV with absorption coefficient of order [Formula: see text][Formula: see text]cm[Formula: see text] in the visible and near infrared range of the solar spectrum were observed.

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Enhanced Absorption in Amorphous Silicon Solar Cells Using Plasmonic and Photonic Crystals – Measurement and Simulation

MRS Proceedings ◽

10.1557/proc-1248-d05-03 ◽

2010 ◽

Vol 1248 ◽

Author(s):

Benjamin Curtin ◽

Rana Biswas ◽

Vikram Dalal

Keyword(s):

Thin Film ◽

Solar Cells ◽

Photonic Crystal ◽

Photonic Crystals ◽

Amorphous Silicon ◽

Near Infrared ◽

Silicon Solar Cells ◽

Back Reflectors ◽

Back Reflector ◽

Hole Arrays

AbstractWe develop experimentally and theoretically plasmonic and photonic crystals for enhancing thin film silicon solar cells. Thin film amorphous silicon (a-Si:H) solar cells suffer from decreased absorption of red and near-infrared photons, where the photon absorption length is large. Simulations predict maximal light absorption for a pitch of 700-800 nm for photonic crystal hole arrays in silver or ZnO/Ag back reflectors, with absorption increases of ~12%. The photonic crystal improves over the ideal randomly roughened back reflector (or the ‘4n2limit’) at wavelengths near the band edge. We fabricated metallic photonic crystal back-reflectors using photolithography and reactive-ion etching. We conformally deposited a-Si:H solar cells on triangular lattice hole arrays of pitch 760 nm on silver back-reflectors. Electron microscopy demonstrates excellent long range periodicity and conformal a-Si:H growth. The measured quantum efficiency increases by 7-8 %, relative to a flat reflector reference device, with enhancement factors exceeding 6 at near-infrared wavelengths. The photonic crystal back reflector strongly diffracts light and increases optical path lengths of solar photons.

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Three-lobed near-infrared Stokes V profiles in the quiet Sun

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732267 ◽

2018 ◽

Vol 616 ◽

pp. A109 ◽

Cited By ~ 2

Author(s):

Christoph Kiess ◽

Juan Manuel Borrero ◽

Wolgang Schmidt

Keyword(s):

Magnetic Properties ◽

Circular Polarization ◽

Optical Depth ◽

Near Infrared ◽

Solar Spectrum ◽

Line Of Sight ◽

Physical Parameters ◽

Solar Photosphere ◽

Complex Signals ◽

Resolution Element

Context. The 1.5-m GREGOR solar telescope can resolve structures as small as 0.4′′ at near-infrared wavelengths on the Sun. At this spatial resolution the polarized solar spectrum shows complex patterns, such as large horizontal and/or vertical variations of the physical parameters in the solar photosphere. Aims. We investigate a region of the quiet solar photosphere exhibiting three-lobed Stokes V profiles in the Fe I spectral line at 15 648 Å. The data were acquired with the GRIS spectropolarimeter attached to the GREGOR telescope. We aim at investigating the thermal, kinematic and magnetic properties of the atmosphere responsible for these measured complex signals. Methods. The SIR inversion code is employed to retrieve the physical parameters of the lower solar photosphere from the observed polarization signals. We follow two different approaches. On the one hand, we consider that the multi-lobe circular polarization signals are only produced by the line-of-sight variation of the physical parameters. We therefore invert the data assuming a single atmospheric component that occupies the entire resolution element in the horizontal plane and where the physical parameters vary with optical depth τ (i.e., line-of-sight). On the other hand, we consider that the multi-lobe circular polarization signals are produced not by the optical depth variations of the physical parameters but instead by their horizontal variations. Here we invert the data assuming that the resolution element is occupied by two different atmospheric components where the kinematic and magnetic properties are constant along the line-of-sight. Results. Both approaches reveal some common features about the topology responsible for the observed three-lobed Stokes V signals: both a strong (>1000 Gauss) and a very weak (<10 Gauss) magnetic field with opposite polarities and harboring flows directed in opposite directions must co-exist (either vertically or horizontally interlaced) within the resolution element. Conclusions.

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