Photovoltaic device

A photovoltaic device, the device comprising:

• a first layer comprising an amorphous silicon semiconductor material of n-type conductivity;
• a second layer comprising a crystalline silicon semiconductor material of p-type conductivity;
• and
• a third layer comprising a non-doped semiconductor material, wherein the third layer is situated between and contacts the first layer and the second layer, and wherein the third layer is a translucent porous layer and diffusion barrier having a thickness of from about 1 nm to about 50 nm.