In this article, high energy-conversion-efficiency N-type back-junction front-contact and back-junction back-contact mono-crystalline silicon solar cells are explored and reviewed in terms of their research and mass-production prospects. The basic physical mechanism of such two types of high-efficiency N-type solar cells is elaborated. Moreover, the current research on N-type IBC solar cells with screen-printed Aluminum belt-firing p+-type emitter is critically addressed. It is considered to be one of the most promising candidates for the evolution of the commercialized P-type crystalline-silicon solar cells.