Photonic and plasmonic crystal based enhancement of solar cells- overcoming the Lambertian classical 4n2 limit

2012 ◽  
Vol 1426 ◽  
pp. 137-147
Author(s):  
Rana Biswas ◽  
Chun Xu ◽  
Sambit Pattnaik ◽  
Joydeep Bhattacharya ◽  
Nayan Chakravarty ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Near Infrared ◽  
Light Trapping ◽  
Infrared Region ◽  
Plasmonic Crystal ◽  
Device Architecture ◽  
Back Reflectors ◽  
Trapping Methods ◽  
Normal Light

ABSTRACTLong wavelength photons in the red and near infrared region of the spectrum are poorly absorbed in thin film silicon cells, due to their long absorption lengths. Advanced light trapping methods are necessary to harvest these photons. The basic physical mechanisms underlying the enhanced light trapping in thin film solar cells using periodic back reflectors include strong diffraction coupled with light concentration. These will be contrasted with the scattering mechanisms involved in randomly textured back reflectors, which are commonly used for light trapping. A special class of conformal solar cells with plasmonic nano-pillar back reflectors will be described, that generates absorption beyond the classical 4n2 limit (the Lambertian limit) averaged over the entire wavelength range for nc-Si:H. The absorption beyond the classical limit exists for common 1 micron thick nc-Si:H cells, and is further enhanced for non-normal light. Predicted currents exceed 31 mA/cm2 for nc-Si:H. The nano-pillars are tapered into conical protrusions that enhance plasmonic effects. Such conformal nc-Si:H solar cells with the same device architecture were grown on periodic nano-hole, periodic nano-pillar substrates and compared with randomly textured substrates, formed by annealing Ag/ZnO or etched Ag/ZnO. The periodic back reflector solar cells with nano-pillars demonstrated higher quantum efficiency and higher photo-currents that were 1 mA/cm2higher than those for the randomly textured back reflectors. Losses within the experimental solar architectures are discussed.

Light trapping efficiency of periodic and quasiperiodic back-reflectors for thin film solar cells: A comparative study

2013 ◽  
Vol 114 (6) ◽  
pp. 063103 ◽  
Author(s):  
A. Micco ◽  
A. Ricciardi ◽  
M. Pisco ◽  
V. La Ferrara ◽  
L. V. Mercaldo ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Comparative Study ◽  
Light Trapping ◽  
Thin Film Solar Cells ◽  
Trapping Efficiency ◽  
Back Reflectors

Light-trapping in Thin Film Silicon Solar Cells with a Combination of Periodic and Randomly Textured Back-reflectors

2012 ◽  
Vol 1426 ◽  
pp. 117-123 ◽  
Author(s):  
Sambit Pattnaik ◽  
Nayan Chakravarty ◽  
Rana Biswas ◽  
D. Slafer ◽  
Vikram Dalal
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Light Absorption ◽  
Nanoimprint Lithography ◽  
Light Trapping ◽  
Silicon Solar Cells ◽  
Long Wavelength ◽  
Thin Film Silicon ◽  
Back Reflectors ◽  
Back Reflector

ABSTRACTLight trapping is essential to harvest long wavelength red and near-infrared photons in thin film silicon solar cells. Traditionally light trapping has been achieved with a randomly roughened Ag/ZnO back reflector, which scatters incoming light uniformly through all angles, and enhances currents and cell efficiencies over a flat back reflector. A new approach using periodically textured photonic-plasmonic arrays has been recently shown to be very promising for harvesting long wavelength photons, through diffraction of light and plasmonic light concentration. Here we investigate the combination of these two approaches of random scattering and plasmonic effects to increase cell performance even further. An array of periodic conical back reflectors was fabricated by nanoimprint lithography and coated with Ag. These back reflectors were systematically annealed to generate different amounts of random texture, at smaller spatial scales, superimposed on a larger scale periodic texture. nc-Si solar cells were grown on flat, periodic photonic-plasmonic substrates, and randomly roughened photonic-plasmonic substrates. There were large improvements (>20%) in the current and light absorption of the photonic-plasmonic substrates relative to flat. The additional random features introduced on the photonic-plasmonic substrates did not improve the current and light absorption further, over a large range of randomization features.

Innovative Device Architecture for High Efficiency Thin Film Silicon Solar Cells

2012 ◽  
Vol 1426 ◽  
pp. 131-135
Author(s):  
Mathieu Boccard ◽  
Matthieu Despeisse ◽  
Christophe Ballif
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
High Efficiency ◽  
Silicon Oxide ◽  
Light Trapping ◽  
Electrical Circuit ◽  
Silicon Solar Cells ◽  
Device Architecture ◽  
Thin Film Silicon ◽  
Photovoltaic Technologies

ABSTRACTThe challenge for all photovoltaic technologies is to maximize light absorption, convert photons with minimal losses to electrical charges and efficiently extract them towards the electrical circuit. For thin film silicon solar cells, a compromise must be found as light trapping is usually performed through textured interfaces, that are detrimental to the subsequent growth of dense and high quality silicon layers. We introduce here the concept of smoothening intermediate reflecting layers (IRL), enabling to combine high currents and good electrical quality in Micromorph devices in the superstrate configuration. After exposing the motivation for such structures, we validate the concept by showing a VOCenhancement when employing a polished silicon-oxide-based IRL. Shunting issues and additional reflection losses are pointed out with such technique, highlighting the need to develop alternative techniques for an efficient morphology adaptation before the microcrystalline silicon cell growth.

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

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.

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

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.

Nanostructured back reflectors produced using polystyrene assisted lithography for enhanced light trapping in silicon thin film solar cells

Solar Energy ◽  
2018 ◽  
Vol 167 ◽  
pp. 108-115 ◽  
Author(s):  
Zeyu Li ◽  
E. Rusli ◽  
Martin Foldyna ◽  
Junkang Wang ◽  
Wanghua Chen ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Light Trapping ◽  
Thin Film Solar Cells ◽  
Silicon Thin Film ◽  
Back Reflectors

SnO2:F with Very High Haze Value and Transmittance in Near Infrared Wavelength for Use as Front Transparent Conductive Oxide Films in Thin-Film Silicon Solar Cells

2013 ◽  
Vol 1536 ◽  
pp. 63-69 ◽  
Author(s):  
Masanobu Isshiki ◽  
Yasuko Ishikawa ◽  
Toru Ikeda ◽  
Takuji Oyama ◽  
Hidefumi Odaka ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Carrier Concentration ◽  
Near Infrared ◽  
Light Trapping ◽  
Flat Glass ◽  
High Mobility ◽  
Transparent Conductive Oxide ◽  
Infrared Wavelength ◽  
Novel Approach

ABSTRACTLow sheet resistance (high mobility) with high transmittance in all wavelength is required for front TCO. High haze value is also required for effective light trapping. For this purpose, we have combined F-doped SnO2 (FTO) with high mobility deposited by LPCVD and reactive ion etching (RIE) processed glass substrate. However, two problems have been found. (1) The mobility of FTO on RIE substrate dropped from that on flat glass (75 to 36 cm2/Vs). To avoid this drop, thicker film is needed. (2) To keep high transmittance with thicker film, lower carrier concentration is needed. But the mobility dropped with lower carrier concentration. In order to solve these constrains, we have adopted a stacked structure using thick non-doped layer of 2700 nm and thin F-doped layer of 500 nm. With this novel approach, we have successfully achieved the high mobility (80 cm2/Vs), low carrier concentration (2.2x1019 /cm3) and high haze value (77% at wavelength of 1000 nm) at the same time. This new developed high-haze SnO2 is a new promising TCO for thin-film Si solar cells.

scholarly journals In and Ga Codoped ZnO Film as a Front Electrode for Thin Film Silicon Solar Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Duy Phong Pham ◽  
Huu Truong Nguyen ◽  
Bach Thang Phan ◽  
Thi My Dung Cao ◽  
Van Dung Hoang ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Solar Cells ◽  
Near Infrared ◽  
Infrared Region ◽  
Silicon Solar Cells ◽  
Zno Film ◽  
Thin Film Silicon ◽  
Wide Range ◽  
Transparent Conducting Electrodes

Doped ZnO thin films have attracted much attention in the research community as front-contact transparent conducting electrodes in thin film silicon solar cells. The prerequisite in both low resistivity and high transmittance in visible and near-infrared region for hydrogenated microcrystalline or amorphous/microcrystalline tandem thin film silicon solar cells has promoted further improvements of this material. In this work, we propose the combination of major Ga and minor In impurities codoped in ZnO film (IGZO) to improve the film optoelectronic properties. A wide range of Ga and In contents in sputtering targets was explored to find optimum optical and electrical properties of deposited films. The results show that an appropriate combination of In and Ga atoms in ZnO material, followed by in-air thermal annealing process, can enhance the crystallization, conductivity, and transmittance of IGZO thin films, which can be well used as front-contact electrodes in thin film silicon solar cells.

Enhancement of light trapping in thin-film hydrogenated microcrystalline Si solar cells using back reflectors with self-ordered dimple pattern

2008 ◽  
Vol 93 (14) ◽  
pp. 143501 ◽  
Author(s):  
Hitoshi Sai ◽  
Hiroyuki Fujiwara ◽  
Michio Kondo ◽  
Yoshiaki Kanamori
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Light Trapping ◽  
Si Solar Cells ◽  
Back Reflectors
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