Novel optoelectronic rotors based on orthorhombic CsPb(Br/I)₃ nanorods

Halide perovskites (HPs) with α-phase have been intensively explored as light absorbers in solar cells, while δ-phase HPs are not suitable for photoelectric application owing to their wider bandgap and less competitive semiconducting properties. Here we propose an innovative light-controlled nanorotor based on δ-CsPb(Br/I)3 nanorods. The one-dimensional lattice structure enables habitual growth of single-crystalline nanorods upon controllable iodide incorporation. The nanorods get polarized under a rotating electric field; when light is applied, photogenerated charge carriers are populated to enhance the torque, overcoming the random Brownian motions to force the rotation of the nanorods. By loading and unloading light, the nanorotor can stably switch between the "ON" and "OFF" states, and the rotating speed can be precisely tailored by tuning the intensity of incident light. This work challenges the commonly-held perception that δ-HP is the undesirable phase, and the light-controlled rotor potentially opens up a new application for HPs.