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Research Papers

Improvement of the Photovoltaic Characteristics of Industrially Fabricated Solar Cells by Chemical Etching of the Si Surface

[+] Author and Article Information
Waheed A. Badawy

Chemistry Department,
Faculty of Science,
Cairo University,
Gamaa Street,
12 613 Giza, Egypt
e-mail: wbadawy@cu.edu.eg or wbadawy50@hotmail.com

Said A. Elmeniawy, Amr N. Hafez

Science and Technology Center of Excellence,
M P P, P.O Box 3066,
Elsalam II, Cairo, Egypt

1Corresponding author.

Contributed by the Solar Energy Division of ASME for publication in the JOURNAL OF SOLAR ENERGY ENGINEERING: INCLUDING WIND ENERGY AND BUILDING ENERGY CONSERVATION. Manuscript received September 4, 2012; final manuscript received March 26, 2014; published online May 28, 2015. Assoc. Editor: Santiago Silvestre.

J. Sol. Energy Eng 137(4), 041007 (Aug 01, 2015) (6 pages) Paper No: SOL-12-1215; doi: 10.1115/1.4027410 History: Received September 04, 2012; Revised March 26, 2014; Online May 28, 2015

The efficiency of industrially fabricated solar cells and hence the power of the solar modules are affected by the surface treatment of the Si-wafers during solar cell fabrication. Surface etching and formation of definite porous structure increase the effective photon flux absorption and lead to higher solar conversion efficiency. Metal-assisted etching of p-Si in aqueous hydrofluoric acid, HF, solutions containing oxidizing agents like potassium bromate, KBrO3, potassium iodate, KIO3, or potassium dichromate, K2Cr2O7, are used for the preparation of well-defined pores. The concentration of both HF and the oxidizing agent and also the time of etching have to be optimized. The electroless deposition of ideal metal nano particles like, Pt or Pd enhances pore formation. The effect of oxidizing agent and its concentration on the main characteristics of the prepared solar cells are investigated and discussed. A comparison with alkali surface treatment with KOH/isopropanol aqueous solution is also considered. In this respect, the manufacturing processes and the tests of the cell are performed in the ARAB INTERNATIONAL OPTRONICS (EGYPT). The morphology of the wafer surfaces is investigated by scanning electron microscopy (SEM) and I-V characteristics of the fabricated cells are investigated by M54A solar tester.

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Figures

Grahic Jump Location
Fig. 1

I-V characteristics of a silicon solar cell after 1 h etching of the Si wafer in 22.0 M HF-0.05 M KIO3 at 25 °C before fabrication

Grahic Jump Location
Fig. 2

(a) Scanning electron micrograph of the etched Si wafer used in the fabrication of the solar cell of Fig. 1 (after 1 h etching of the Si wafer in 22.0 M HF-0.05 M KIO3 at 25 °C). (b) Scanning electron micrograph of the Si wafer after 3 h etching in 22.0 M HF-0.05 M KIO3 at 25 °C.

Grahic Jump Location
Fig. 3

I-V characteristics of a silicon solar cell after 30 min pre-etching of the Si wafer in 3 M KOH + 2 M IPA solution at 70 °C then, electroless deposition of platinum and etching in 22.0 M HF-0.05 M KIO3 for 1 h at 25 °C

Grahic Jump Location
Fig. 4

Scanning electron micrograph of Si wafer after 30 min pre-etching of the Si wafer in 3 M KOH + 2 M IPA solution at 70 °C then, electroless deposition of platinum and etching in 22.0 M HF-0.05 M KIO3 for 1 h at 25 °C

Grahic Jump Location
Fig. 5

Scanning electron micrograph of Si wafer after 30 min pre-etching of the Si wafer in 3 M KOH + 2 M IPA solution at 70 °C then, electroless deposition of palladium and etching in 22.0 M HF-0.05 M KIO3 for 1 h at 25 °C

Grahic Jump Location
Fig. 6

I-V characteristics of a silicon solar cell after 10 min pre-etching the Si-wafer in 10% NaOH for 10 min at 25 °C, then etching in 3 M KOH + 2 M IPA aqueous solution for 30 min at 70 °C

Grahic Jump Location
Fig. 7

SE micrograph of the Si-wafer after 10 min pre-etching in 10% NaOH for 10 min at 25 °C, then etching in 3 M KOH + 2 M IPA aqueous solution for 30 min at 70 °C

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