الفهرس 
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Abstract
In recent years, pollution problems are increasing continuously so we must develop the renewable energy sources especially the sun light because in Egypt the sun is shiny every day approximately. Solar cells or photovoltaic cells are the most commercially cleanest way to getting this goal. But the high cost of fabricating solar cells was the big problem of the non widespread of these cells, so it had to searching another way with low cost. The Dye Sensitized Solar Cell (DSSC) was attractive the attention recently due to its high efficiency and low cost of fabricating. It consists of two electrodes (the photo or working electrode and the counter electrode) and the electrolyte in between of them.
Silicon is the second most abundant element in the earth crust it makes 27.7% of the earth crust. It belongs to semiconductors element. Silicon is classified as a metalloid it has properties that are similar to both metals and nonmetals. It is known as silicon wafer in semiconductor industry. Czochralski growth (known as CZ wafers) is the most economical method for producing silicon wafers.
By electrochemical etching process porous silicon is fabricated with large surface area and sponge shape. Electrochemical etching is the most popular technique used to fabricate porous silicon layers. It consists of two electrode cathode (usually is platinum) and anode (usually is silicon sample) and HF based electrolyte.
In our work we fabricated DSSC by using porous silicon layer as a photo electrode one time and as a counter electrode another time. We fabricate different samples with different etching time at constant etching current density and HF concentration.
For PS layer we studied the structural properties by using scanning electron microscope (SEM) and optical properties by Photoluminescence (PL) and UV-Vis spectroscopy (UV) and compared the energy band gap.
For PSDSSC we studied the J-V characteristic curve and calculated the fill factor and the efficiency which were increasing by increasing the etching time.
Keywords.
Photovoltaics, Dye-sensitized solar cell, Porous Silicon, Electrochemical etching.