Improved Photon Absorption in a-Si:H Solar Cells using Photonic Crystal Architectures

2008 ◽  
Vol 1066 ◽  
Author(s):  
Rana Biswas ◽  
Dayu Zhou
Keyword(s):  
Solar Cells ◽  
Photonic Crystal ◽  
Light Trapping ◽  
Optical Path Length ◽  
Bragg Reflector ◽  
Photon Absorption ◽  
Distributed Bragg Reflector ◽  
Near Ir ◽  
Back Reflectors ◽  
Major Route

ABSTRACTImproved light-trapping is a major route to improving solar cell efficiencies. We design a combination of a 2-dimensional photonic crystal and a one-dimensional distributed Bragg reflector as the back reflector for a-Si:H solar cells. This configuration avoids inherent losses associated with textured back-reflectors. The photonic crystals are composed of ITO and can easily serve as a conducting back contact. We have optimized the geometry of the photonic crystal to maximize absorption using rigorous scattering matrix simulations. The photonic crystal provides strong diffraction of red and near-IR wavelengths within the absorber layer and can enhance the absorption by more than a factor of 10 relative to the case without the photonic crystal. The optical path length with the photonic crystal can improve over the limit for a random roughened scattering surface.

New Light Trapping in Thin Film Solar Cells Using Textured Photonic Crystals

2005 ◽  
Vol 862 ◽  
Author(s):  
Lirong Zeng ◽  
Yasha Yi ◽  
Ching-Yin Hong ◽  
Xiaoman Duan ◽  
Lionel C. Kimerling
Keyword(s):  
Solar Cells ◽  
Path Length ◽  
Light Trapping ◽  
Optical Path Length ◽  
Optical Path ◽  
Bragg Reflector ◽  
Distributed Bragg Reflector ◽  
Solar Cell Efficiency ◽  
Cell Efficiency ◽  
Reflection Grating

AbstractA novel light trapping scheme is developed to enhance the optical path length in solar cells by using a photonic structure as the backside reflector. This structure combines a reflection grating on the substrate with an over-deposited distributed Bragg reflector (DBR). With this structure, the optical path length can be enhanced by more than 104 times with very little reflection loss. In turn, solar cell efficiency is predicted to be enhanced enormously.

Optimization of Textured Photonic Crystal Backside Reflector for Si Thin Film Solar Cells

2006 ◽  
Vol 974 ◽  
Author(s):  
Lirong Zeng ◽  
Peter Bermel ◽  
Yasha Yi ◽  
Ning-ning Feng ◽  
Bernard A. Alamariu ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Photonic Crystal ◽  
Bragg Reflector ◽  
Thin Film Solar Cells ◽  
Etch Depth ◽  
Optimized Design ◽  
Efficiency Enhancement ◽  
Distributed Bragg Reflector ◽  
Si Thin Film

ABSTRACTA new backside reflector, textured photonic crystal, is introduced into Si thin film solar cells. Scattering matrix method is used to systematically optimize all the parameters of the two components of the backside reflector, grating and distributed Bragg reflector, to achieve the highest power conversion efficiency for a given solar cell thickness. Experimentally, Si-on-insulator solar cells are being fabricated to verify the tremendous efficiency enhancement and optimal design. It is found that while the optimal period and etch depth of the grating, the Bragg wavelength of the distributed Bragg reflector, as well as the antireflection coating thickness all decrease as the cell becomes thinner, the optimum duty cycle of the grating remains almost constant at 0.5. For a 2 μm thick cell, the relative efficiency enhancement can be as high as 52% using the optimized design.

Enhancing Light-trapping and Efficiency of Solar Cells with Photonic Crystals

2007 ◽  
Vol 989 ◽  
Author(s):  
Rana Biswas ◽  
Dayu Zhou
Keyword(s):  
Solar Cells ◽  
Photonic Crystal ◽  
Photonic Crystals ◽  
Amorphous Silicon ◽  
Near Infrared ◽  
Light Trapping ◽  
Absorber Layer ◽  
Diffract Light ◽  
Major Route ◽  
Optical Wavelengths

AbstractA major route to improving solar cell efficiencies is by improving light trapping in solar absorber layers. Traditional light trapping schemes involve a textured metallic back reflector that also introduces losses at optical wavelengths. Here we develop alternative light trapping schemes with a-Si:H thin film solar cells, that do not use metallic components, thereby avoiding losses. We utilize low loss one-dimensional photonic crystals as distributed Bragg reflectors (DBR) at the backside of the solar cells. The DBR is constructed with alternating layers of crystalline Si and SiO2. Between the DBR and the absorber layer, there is a layer of 2D photonic crystal composed of amorphous silicon and SiO2. The 2D photonic crystal layer will diffract light at oblique angles, so that total internal reflection is formed inside the absorber layer. We have achieved enhanced light-trapping in both crystalline and amorphous silicon solar cells at near-infrared wavelengths where absorption lengths are very large. Very high absorption is achieved throughout optical wavelengths. The optical modeling is performed with a rigorous 3 dimensional scattering matrix approach where Maxwell¡¯s equations are solved in Fourier space.

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.

New Solar Cells with Novel Light Trapping via Textured Photonic Crystal Back Reflector

2005 ◽  
Vol 891 ◽  
Author(s):  
Lirong Zeng ◽  
Yasha Yi ◽  
Ching-yin Hong ◽  
Bernard A. Alamariu ◽  
Jifeng Liu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Photonic Crystal ◽  
Path Length ◽  
Minority Carrier ◽  
Diffusion Length ◽  
Light Trapping ◽  
Optical Path Length ◽  
Minority Carrier Diffusion Length ◽  
Si Solar Cells ◽  
Back Reflector

ABSTRACTWe have successfully developed a new light-trapping scheme for solar cells that can enhance the optical path length by more than 104 times using a textured photonic crystal structure as a backside reflector. Top-contacted crystalline Si solar cells integrated with the new back reflector were designed, fabricated and characterized. Both external quantum efficiency and power conversion efficiency of the cells have shown significant improvement due to the path length enhancement furnished by the new back reflector despite of the 675 um thick wafers and relatively short minority carrier diffusion length.

Photonic crystal enhanced light-trapping in thin film solar cells

2008 ◽  
Vol 103 (9) ◽  
pp. 093102 ◽  
Author(s):  
Dayu Zhou ◽  
Rana Biswas
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Photonic Crystal ◽  
Light Trapping ◽  
Thin Film Solar Cells

Design and Fabrication of an Irregularly Shaped Distributed Bragg Reflector for Hetero-Junction with Intrinsic Thin Layer Solar Cells

2013 ◽  
Vol 33 (9) ◽  
pp. 0931003
Author(s):  
周健 Zhou Jian ◽  
李红飞 Li Hongfei ◽  
刘毓成 Liu Yuchen ◽  
谈惠祖 Tan Huizu ◽  
刘正新 Liu Zhengxin
Keyword(s):  
Solar Cells ◽  
Thin Layer ◽  
Bragg Reflector ◽  
Distributed Bragg Reflector

scholarly journals Light trapping in hydrogenated amorphous and nano-crystalline silicon thin film solar cells

2009 ◽  
Vol 1153 ◽  
Author(s):  
Jeffrey Yang ◽  
Baojie Yan ◽  
Guozhen Yue ◽  
Subhendu Guha
Keyword(s):  
Stainless Steel ◽  
Solar Cells ◽  
Triple Junction ◽  
Crystalline Silicon ◽  
Light Trapping ◽  
Nano Crystalline ◽  
Back Reflectors ◽  
Back Reflector ◽  
Junction Structure ◽  
Hydrogenated Amorphous

AbstractLight trapping effect in hydrogenated amorphous silicon-germanium alloy (a-SiGe:H) and nano-crystalline silicon (nc-Si:H) thin film solar cells deposited on stainless steel substrates with various back reflectors is reviewed. Structural and optical properties of the Ag/ZnO back reflectors are systematically characterized and correlated to solar cell performance, especially the enhancement in photocurrent. The light trapping method used in our current production lines employing an a-Si:H/a-SiGe:H/a-SiGe:H triple-junction structure consists of a bi-layer of Al/ZnO back reflector with relatively thin Al and ZnO layers. Such Al/ZnO back reflectors enhance the short-circuit current density, Jsc, by ˜20% compared to bare stainless steel. In the laboratory, we use Ag/ZnO back reflector for higher Jsc and efficiency. The gain in Jsc is about ˜30% for an a-SiGe:H single-junction cell used in the bottom cell of a multi-junction structure. In recent years, we have also worked on the optimization of Ag/ZnO back reflectors for nano-crystalline silicon (nc-Si:H) solar cells. We have carried out a systematic study on the effect of texture for Ag and ZnO. We found that for a thin ZnO layer, a textured Ag layer is necessary to increase Jsc, even though the parasitic loss is higher at the Ag and ZnO interface due to the textured Ag. However, a flat Ag can be used for a thick ZnO to reduce the parasitic loss, while the light scattering is provided by the textured ZnO. The gain in Jsc for nc-Si:H solar cells on Ag/ZnO back reflectors is in the range of ˜60-75% compared to cells deposited on bare stainless steel, which is much larger than the enhancement observed for a-SiGe:H cells. The highest total current density achieved in an a-Si:H/a-SiGe:H/nc-Si:H triple-junction structure on Ag/ZnO back reflector is 28.6 mA/cm2, while it is 26.9 mA/cm2 for a high efficiency a-Si:H/a-SiGe:H/a-SiGe:H triple-junction cell.

scholarly journals Optimal light trapping in ultra-thin photonic crystal crystalline silicon solar cells

2010 ◽  
Vol 18 (6) ◽  
pp. 5691 ◽  
Author(s):  
Shrestha Basu Mallick ◽  
Mukul Agrawal ◽  
Peter Peumans
Keyword(s):  
Solar Cells ◽  
Photonic Crystal ◽  
Crystalline Silicon ◽  
Light Trapping ◽  
Silicon Solar Cells ◽  
Crystalline Silicon Solar Cells
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