19% Efficient Thin-Film Crystalline Silicon Solar Cells From Layer Transfer Using Porous Silicon: A Loss Analysis by Means of Three-Dimensional Simulations

AbstractThin film silicon solar cells, consisting of an epitaxially grown active layer on a low quality highly doped silicon substrate, incorporate many attractive features usually associated with their sister cells based on bulk silicon. However, the efficiency of the current epitaxial semi-industrial screen printed cells is limited to 11-12% mainly due to optical shortcomings. This paper will give an overview of our work aimed at tackling the 2 most important problems: (i) Finding and implementing an adequate front surface texture and (ii) the simulation, fabrication and incorporation of an intermediate reflector.The former issue has been addressed by the development of plasma texturing based on halogen species. This method allows us to fulfil the sometimes contradictory requirements for the textured surface, i.e. a uniform and reduced reflection, a strong lambertian character to scatter the light and a limited removal of silicon. It will be shown that the scattering efficiency is dependent on both the wavelength of the impinging light and on the silicon removal during the texturing process.The second and main issue of this work is the limited absorption volume of the epitaxial layer. To resolve this drawback, an intermediate reflector is placed at the epi/substrate interface to enhance the path length of the low energy photons through the epi-layer. In practice, a multi-layer porous silicon stack is created by electrochemical anodization of the substrate. The reflection at the epi/reflector/substrate interface is a combination of several different effects including a Bragg mirror and Total Internal Reflection (TIR). Measurements of the external reflectance as well as extraction of the internal reflection parameters are used to clarify the issue. Advanced structures, including chirped porous silicon stacks, are introduced. Finally, the benefits of the reflector on the level of the epitaxial silicon solar cell are analysed. Efficiencies close to 14% are obtained for epitaxial cells incorporating an advanced porous Si reflector.

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Titanium oxide electron-selective layers for contact passivation of thin-film crystalline silicon solar cells

10.1117/12.2213540 ◽

2016 ◽

Cited By ~ 1

Author(s):

Yi Liu ◽

Yusi Chen ◽

David T. LaFehr ◽

Yen Su ◽

Yijie Huo ◽

...

Keyword(s):

Thin Film ◽

Solar Cells ◽

Titanium Oxide ◽

Crystalline Silicon ◽

Silicon Solar Cells ◽

Crystalline Silicon Solar Cells

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Porous silicon in crystalline silicon solar cells: a review and the effect on the internal quantum efficiency

Progress in Photovoltaics Research and Applications ◽

10.1002/(sici)1099-159x(199807/08)6:4<233::aid-pip207>3.0.co;2-d ◽

1998 ◽

Vol 6 (4) ◽

pp. 233-246 ◽

Cited By ~ 61

Author(s):

L. Stalmans ◽

J. Poortmans ◽

H. Bender ◽

M. Caymax ◽

K. Said ◽

...

Keyword(s):

Solar Cells ◽

Porous Silicon ◽

Quantum Efficiency ◽

Crystalline Silicon ◽

Internal Quantum Efficiency ◽

Silicon Solar Cells ◽

Crystalline Silicon Solar Cells

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Effects of Electrochemical Etching Time on the Performance of Porous Silicon Solar Cells on Crystalline n-Type (100) and (111)

Journal of Nano Research ◽

10.4028/www.scientific.net/jnanor.46.45 ◽

2017 ◽

Vol 46 ◽

pp. 45-56 ◽

Cited By ~ 3

Author(s):

Khalid Omar ◽

Khaldun A. Salman

Keyword(s):

Solar Cells ◽

Porous Silicon ◽

Crystalline Silicon ◽

Electrochemical Etching ◽

Silicon Layer ◽

Porous Silicon Layer ◽

Silicon Solar Cells ◽

Etching Time ◽

Crystalline Silicon Solar Cells ◽

Coating Layers

Electrochemical etching was carried out to produce porous silicon based on crystalline silicon n-type (100) and (111) wafers. Etching times of 10, 20, and 30 min were applied. Porous silicon layer was used as anti-reflection coating on crystalline silicon solar cells. The optimal etching time is 20 min for preparing porous silicon layers based on crystalline silicon n-type (100) and (111) wafers. Nanopores with high porosity were produced on the porous silicon layer based on crystalline silicon n-type (100) and (111) wafers with average diameters of 5.7 and 5.8 nm, respectively. Average crystallite sizes for the porous silicon layer based on crystalline silicon n-type (100) and (111) wafers were 20.57 and 17.45 nm at 20 and 30 min, respectively, due to the increase in broadening of the full width at half maximum. Photoluminescence peaks for porous silicon layers based on crystalline silicon n-type (100) and (111) wafers increased with growing porosity and a great blue shift in luminescence. The minimum effective coefficient of reflection was obtained from porous silicon layers based on the crystalline silicon n-type (100) wafer compared with n-type (111) wafer and as-grown at different etching times. Porous silicon layers based on the crystalline silicon n-type (100) wafer at 20 min etching time exhibited excellent light trapping at wavelengths ranging from 400 to 1000 nm. Thus, fabricated crystalline silicon solar cells based on porous silicon (100) anti-reflection coating layers achieved the highest efficiency at 15.50% compared to porous silicon (111) anti-reflection coating layers. The efficiency is characterized applying I-V characterization system under 100 mW/cm2 illumination conditions.

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