**Abstract**

Nanowires (NWs) are 1D nanostructures with unique and wonderful optical and electrical properties. Due to their highly anisotropic shape and enormous index of refraction, they behave as optical antennae with improved absorption and emission properties, and thus better photovoltaic cell efficiency compared to a planar material with equivalent volume. Implying important advantages of reduced material usage and cost as well as due to its direct bandgap and its flexibility for designing solar cells, we choose to review III–V NWs. Their bandgap can easily be tunable for growing on the cheapest Si substrate. The recent developments in NW-based photovoltaics with attractive III–V NWs with different growth mechanisms, device fabrication, and performance results are studied. Recently, III–V NW solar cells have achieved an interesting efficiency above 10%. GaAsP NW has achieved 10.2%; InP NW has achieved 13.8%; GaAs NW has achieved 15.3%; and moreover the highest 17.8% efficiency is achieved by InP NW. While the III–V NW solar cells are much more vital and promising, their current efficiencies are still much lower than the theoretically predicted maximum efficiency of 48%. In this review, the chapter focused on the synthesis processes of III–V nanowires, vapor-liquid-solid growing mechanisms, solar light harvesting of III–V nanowire solar cells, and designing high-efficiency and low-cost III–V nanowire solar cells.

**Keywords:** III–V nanowires, nanowire design, nanowire synthesis, photovoltaic, solar cells
