A switchable optical element for use in a smart window, comprising - a pair of substrates (2a, 2b) disposed facing each other and separated from each other - at least one cell arranged between the pair of substrates and laterally extending between the pair of substrates, and comprising a dispersion of charged scattering particles, - a cell electrode configuration provided on said pair of substrates and organized into groups of cell electrodes with cell electrodes of a first group being interleaved with cell electrodes of a second group on a face of a first one of the pair of substrates and cell electrodes of a third group being interleaved with cell electrodes of a fourth group on a face of a second one of the pair of substrates, said cell electrode configuration on said pair of substrates further defining a transport region and a confinement region of said at least one cell, the transport region being contiguous with the confinement region, wherein the at least one cell is switchable between a first optical state and a second optical state, the first optical state being associated with a light-scattering, distributed configuration of the scattering particles within the transport and confinement region of said at least one cell, and the second optical state being associated with a non-scattering, confined configuration of the scattering particles within the confinement region of said at least one cell, wherein a relative arrangement between the cell electrodes of the first and second group (7A, 7B) on the first substrate relative to the cell electrodes of the third and fourth group (7C, 7D) on the second substrate is adapted for inducing lateral transport conditions for the scattering particles in the at least one cell, from the transport region towards the confinement region, when control signals for switching of the at least one cell between the two optical states are received by the electrode configuration, and wherein the transport region of the at least one cell and the therein induced lateral transport of the charged scattering particles extends over at least a distance corresponding to two adjacent cell electrodes of one same group of said groups of cell electrodes in the lateral direction of the cell. - a pair of substrates (2a, 2b) disposed facing each other and separated from each other - at least one cell arranged between the pair of substrates and laterally extending between the pair of substrates, and comprising a dispersion of charged scattering particles, - a cell electrode configuration provided on said pair of substrates and organized into groups of cell electrodes with cell electrodes of a first group being interleaved with cell electrodes of a second group on a face of a first one of the pair of substrates and cell electrodes of a third group being interleaved with cell electrodes of a fourth group on a face of a second one of the pair of substrates, said cell electrode configuration on said pair of substrates further defining a transport region and a confinement region of said at least one cell, the transport region being contiguous with the confinement region, wherein the at least one cell is switchable between a first optical state and a second optical state, the first optical state being associated with a light-scattering, distributed configuration of the scattering particles within the transport and confinement region of said at least one cell, and the second optical state being associated with a non-scattering, confined configuration of the scattering particles within the confinement region of said at least one cell, wherein a relative arrangement between the cell electrodes of the first and second group (7A, 7B) on the first substrate relative to the cell electrodes of the third and fourth group (7C, 7D) on the second substrate is adapted for inducing lateral transport conditions for the scattering particles in the at least one cell, from the transport region towards the confinement region, when control signals for switching of the at least one cell between the two optical states are received by the electrode configuration, and wherein the transport region of the at least one cell and the therein induced lateral transport of the charged scattering particles extends over at least a distance corresponding to two adjacent cell electrodes of one same group of said groups of cell electrodes in the lateral direction of the cell.