An efficient solar cell and method of fabricating the same is disclosed. The solar cell includes an n-doped substrate layer. A p-doped buffer layer is disposed on the n-doped substrate layer. A quantum dot absorber stack is disposed on the buffer layer. The absorber stack includes at least one quantum dot layer and one p-doped spacer layer. A p-doped cap layer is disposed on the quantum dot absorber layer. The thickness of the quantum dot layer is less than an electron diffusion length from the depletion region formed by the n-doped substrate layer and the p-doped buffer layer. The quantum dot absorber layer allows for additional photo currents from two-photon absorption from the p-doped cap layer being exposed to a light source.