Patent ID: 7301215

Claim:
A photovoltaic device comprising: a first electrode; a first-conductivity-type layer composed of non-single-crystalline silicon; a second-conductivity-type layer composed of polycrystalline silicon; a third-conductivity-type layer composed of non-single-crystalline silicon; and a second electrode, wherein a contact surface of the first electrode with respect to the first-conductivity-type layer has a shape interspersed with a plurality of projections, and the lower limit and the upper limit of the density of the projections interspersed on the surface of the first electrode satisfy the following equations, provided that the thickness of the second-conductivity-type layer is t μm: Lower limit=0.312 exp(−0.60 t ) pieces/μm 2 Upper limit=0.387 exp(−0.39 t ) pieces/μm 2 .