Abstract: A manufacturing method of a solar cell includes the following steps, providing a substrate, which includes a first conductivity type semi-conductor layer and a second conductivity type semi-conductor layer. The conductivity type of the first conductivity type semi-conductor layer is opposite to the conductivity type of the second conductivity type semi-conductor layer. A graphene oxide layer is formed on the substrate and the graphene oxide layer contacts with the second conductivity type semi-conductor layer. A first electrode and a second electrode are formed on the substrate. The first electrode contacts with the first conductivity type semi-conductor layer, and the second electrode contacts with the second conductivity type semi-conductor layer.