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

Abstract

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.