A study of built-in potential ina-Si solar cells by means of back-surface reflected electroabsorption

Abstract We have investigated the effect of emitter design key parameters such as depth factor and the peak concentration for different types of emitter diffusion profiles (uniform, exponential, Gaussian, and Erfc) on the performance of silicon (Si) solar cells. The value of the depth factor is optimized as 0.1 µm for all these emitter diffusion profiles. Afterward, the peak concentration value is optimized for all the diffusion profiles. A close examination of relative diffusion lengths, conductivities, recombination rates, internal and external quantum efficiencies for these diffusion profiles revealed that among all the considered emitter diffusion profiles, the Erfc profile exhibits the maximum efficiency of 23.53% with an optimized peak concentration of 2×1020 cm-3 for emitter and 1×1019 cm-3 for the back surface filed doping. PC1D was used for all the simulations.

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Screen-Printed Al Back Contacts on Si Solar Cells: Issues and Some Solutions

MRS Proceedings ◽

10.1557/proc-1210-q05-02 ◽

2009 ◽

Vol 1210 ◽

Author(s):

Vishal Mehta ◽

Bhushan Sopori ◽

Robert Reedy ◽

Bobby To ◽

Helio Moutinho ◽

...

Keyword(s):

Surface Tension ◽

Solar Cells ◽

Basic Problem ◽

Series Resistance ◽

Back Surface ◽

Al Alloy ◽

Back Contact ◽

Back Surface Field ◽

Si Solar Cells ◽

Surface Field

AbstractThis paper identifies some mechanisms that lead to problems in back Al contact formation. Major issues are related to a basic problem that the Al melt has a large surface tension and tries to ball up during the firing step. Other issues arise from dissolution of the Si-Al interface and entrapment of glass within the Si-Al alloy. Si diffusion into Al can be applied to control the melt, while cooling rate can help improve the structure of various regions of the back contact for a favorable series resistance. We also discuss a modified time-temperature profile that can lead to a deep and uniform back-surface field.

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The Effect of the Doping Profile in Aluminum Back-Surface-Field on the Electronic Properties of c-Si Solar Cells

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.1690 ◽

2010 ◽

Vol 654-656 ◽

pp. 1690-1693

Author(s):

Ji Cheng Zhou ◽

Yong Min Chen

Keyword(s):

Solar Cells ◽

Electronic Properties ◽

Doping Profile ◽

Back Surface ◽

Optimum Thickness ◽

Atomic Concentration ◽

Si Solar Cells ◽

Surface Field ◽

Maximum Value ◽

Heavily Doped

The electronic properties of the solar cells were greatly influenced by the aluminum atomic concentration in Al-BSF region under that the Al-BSF is doped heavily. The effects of the dopincg profile in heavily-doped Al-BSF on electronic properties of n+pp+ monocrystalline solar cells were investigated by PC1D. The results show that the electronic properties of solar cells are almost independent of the doping profile of the Al-BSF, but are more or less affected by the BSF profile if the solar cell back surface is passivated well with the BSRV less than ~105cm/s. When the sheet resistance is about between 5 and 30Ω/□, the conversion efficiency can reach the maximum value. And the optimum thickness of Al-BSF is about between 10~15μm.

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