Fig. 1: Effect of light on [CoGa] crystals at the microscopic and macroscopic scale.

a Schematic representation of the energy storage and conversion mechanism upon light irradiation. Due to the crystallization in a polar space group, molecular dipole switching is manifested as macroscopic polarization switching upon light excitation which produces an excited polarization state (higher polarization state) with long lifetime (energy storage). Relaxation from the trapped metastable state induces macroscopic polarization switching which generates an electric current in the external circuit (energy conversion). b Mechanism of the light and thermally induced polarization change; electron transfer between cobalt and ligand. c Crystal packing of the complex which favors unidirectional electron transfer inside the lattice. (color code: cobalt—orange, gallium—dark green, carbon—grey, oxygen—red, nitrogen—blue, phosphorus—pink, fluorine—light green, hydrogen atoms are omitted for structural clarity).