Functional semiconductor-ionic materials can be used to realize a single component or so-called three-in-one fuel cell design. Such materials integrate the functionalities of fuel cell's anode, electrolyte, and cathode into one component. The underlying principle of a single-component fuel cell design combines material band structures with ionic species/transport. The performance values of such devices could exceed that of traditional fuel cells. This could represent a major progress in fuel cell science and technology and lies grounds for a new direction of fuel cell R&D and commercialization.