III-V photovoltaics - Recent developments and prospects

III-V materials are the unchallenged front runner for high-efficiency photovoltaics. This high-efficiency arises from the tunability of the materials system. In particular, III-Vs can be epitaxially grown and, by varying the stoichiometry of binary (ternary or quarternary) systems, the lattice parameter can be controlled to yield devices with very low crystal defect density and simultaneously result in different band gaps. Thus, one p-n junction can be grown epitaxially on top of the next, each absorbing a different portion of the solar spectrum - ultimately yielding multiple p-n junctions in tandem with the ability to harness the solar spectrum more efficiently than a single junction or a typical silicon-based solar cell. Furthermore, III-V photovoltaics have the dual advantage of being applicable in thin-film form and to operate under high concentration. There lies the beauty of III-V photovoltaics. This dual ability is lacking in Si- and CIGS-based PV. ©The Electrochemical Society.