A solar cell includes a back metal-contact layer, a P-type semiconductor layer, a P-N junction layer, an N-type semiconductor layer and a transparent electrically conductive layer. The P-type semiconductor layer is formed on the back metal-contact layer. The P-type semiconductor layer is comprised of nano particles of a P-type semi-conductive compound. The P-N junction layer is formed on the P-type semiconductor layer. The N-type semiconductor layer is formed on the P-N junction layer. The N-type semiconductor layer is comprised of nano particles of an N-type semi-conductive compound. The transparent electrically conductive layer is formed on the N-type semiconductor layer and functions as a front contact layer.