The scale of renewable energy challenge not only calls for highly efficient technologies but also abundant, inexpensive, and robust materials.Nanomaterials such as one-dimensional (1D) nanowires can help to mitigate the poor properties of earth-abundant semiconductors to enhance solar energy conversion.[1] I will first discuss a new growth mechanism of nanowires and nanomaterials, in which screw dislocation defects provide the selfperpetuating steps to enable anisotropic crystal growth.