PHOTOVOLTAIC DEVICES

1 . A photovoltaic device comprising:

a substrate;

a transparent conductive layer deposited on the substrate;

a semiconductor layer including a P layer, an I layer, and a N layer sequentially deposited on the transparent conductive layer, wherein the P layer is a P-type oxide semiconductor; and

a rear electrode deposited on the N layer.

2 . The photovoltaic device of claim 1 , wherein

the difference of the band gap between the P layer and the I layer is in the range of about 1.5 eV to about 2.5 eV.

3 . The photovoltaic device of claim 1 further comprising

a buffer layer disposed between the P layer and the I layer for buffering the difference of the band gap between the P layer and the I layer.

4 . The photovoltaic device of claim 3 , wherein

the buffer layer is made of one selected from a group of amorphous carbon (a-C), amorphous silicon carbide (a-SiC), and amorphous silicon oxide (a-SiO).

5 . The photovoltaic device of claim 3 , wherein

the P-type oxide semiconductor includes at least one of Ga, In, Zn, Sn, Cu, Al, Sr, La, and Hf.

6 . The photovoltaic device of claim 5 , wherein

the P-type oxide semiconductor is made of at least one of CuAlO 2 , CuGaO 2 , SrCu 2 O 2 , and (LaO)CuS.

7 . The photovoltaic device of claim 1 , wherein

the band gap of the P-type oxide semiconductor is in the range of about 3.0 eV to about 3.5 eV.

8 . The photovoltaic device of claim 1 , wherein

the thickness of the P-type oxide semiconductor is in the range of about 200 Å to about 1000 Å.

9 . The photovoltaic device of claim 1 , wherein

the I layer is made of at least one selected from a group of amorphous silicon (a-Si), microcrystalline silicon (μc-Si), monocrystalline silicon (Si), cardmium telluride (CdTe), copper-indium-gallium-selenium (CIGS), and gallium arsenide (GaAs).

10 . The photovoltaic device of claim 9 , wherein

the thickness of the I layer is in the range of about 3000 Å to about 6000 Å.

11 . The photovoltaic device of claim 9 , wherein the thickness of the transparent conductive layer is in the range of about 7000 Å to about 10,000 Å.

12 . The photovoltaic device of claim 1 , wherein

the band gap of the I layer is in the range of about 1.0 eV to about 2.0 eV.

13 . The photovoltaic device of claim 1 , wherein

the semiconductor layer is made of a multi-layered structure in which the P layer, the I layer, and the N layer are sequentially deposited a plurality of times.

14 . The photovoltaic device of claim 1 , wherein

the P layer and the I layer have different band gaps.

15 . A photovoltaic device comprising:

a substrate;

a transparent conductive layer deposited on the substrate;

a semiconductor layer provided with a N layer, an I layer, and a P layer sequentially deposited on the transparent conductive layer, wherein the N layer is a N-type oxide semiconductor; and

a rear electrode deposited on the P layer of the semiconductor layer.

16 . The photovoltaic device of claim 15 , wherein:

the difference of the band gap between the N layer and the I layer is in the range of about 1.5 eV to about 2.5 eV.

17 . The photovoltaic device of claim 16 , wherein:

the N-type oxide semiconductor includes at least one of Ga, In, Zn, Sn, Cu, Al, Sr, La, and Hf.

18 . The photovoltaic device of claim 17 , wherein

the N-type oxide semiconductor is made of at least one of AgInO2, AlO, and ZnO doped with an impurity at a low concentration.

19 . The photovoltaic device of claim 15 further comprising

a buffer layer disposed between the N layer and the I layer for buffering the difference of the band gap between the N layer and the I layer.

20 . The photovoltaic device of claim 15 , wherein

the I layer is made of at least one selected from a group of amorphous silicon (a-Si), microcrystalline silicon (μc-Si), mono crystalline silicon (Si), a cardmium telluride (CdTe), copper-indium-gallium-selenium (CIGS), and gallium arsenide (GaAs).

21 . The photovoltaic device of claim 20 , further comprising

a reflecting electrode disposed between the substrate and the transparent conductive layer.

22 . The photovoltaic device of claim 20 , further comprising

a connection electrode formed on the rear electrode.

23 . A method for manufacturing a photovoltaic device comprising:

depositing a transparent conductive layer on a substrate;

patterning the transparent conductive layer;

forming a semiconductor layer including a P layer, an I layer, and a N layer sequentially deposited on the patterned transparent conductive layer, wherein the P layer is made of a P-type oxide semiconductor;

patterning the semiconductor layer;

forming a rear electrode layer on the patterned semiconductor layer; and

patterning the rear electrode layer and the semiconductor layer.

24 . The method of claim 23 , further comprising

texture-treating the surface of the transparent conductive layer to form a texture layer after depositing the transparent conductive layer.

25 . The method of claim 23 , wherein

the transparent conductive layer, the semiconductor layer, and the rear electrode layer are patterned by laser scribing.

26 . A method for manufacturing a photovoltaic device, comprising:

depositing a transparent conductive layer on a substrate;

forming a P layer on the transparent conductive layer, wherein the P layer is made of a P-type oxide semiconductor;

patterning the transparent conductive layer and the P layer;

sequentially depositing an I layer and a N layer on the P layer;

patterning a semiconductor layer including the P layer, the I layer, and the N layer;

forming a rear electrode layer on the patterned semiconductor layer; and

patterning the rear electrode layer and the semiconductor layer.

27 . The method of claim 26 , further comprising

texture-treating the surface of the transparent conductive layer to form a texture layer after depositing the transparent conductive layer.

28 . The method of claim 26 , wherein

the transparent conductive layer, the semiconductor layer, and the rear electrode layer are patterned by laser scribing.