The reverse process, i.e., the inverse Rashba–Edelstein effect (I(R)EE) occurs when a spin accumulation is generated inside the investigated material and a consequent charge current arises on the material surface (in this case, we have a 2D spin-to-charge conversion). In order to have the inverse Rashba–Edelstein effect, a spin accumulation is required to be generated inside the analyzed material and this spin injection is usually achieved by coupling the material under investigation with a ferromagnet in order to perform the spin pumping or with a semiconductor where it is possible to perform optical orientation. As for the direct effect, the inverse Rashba–Edelstein effect occurs in materials lacking the structural inversion symmetry, while in topological insulators the inverse Edelstein effect arises.