The present invention relates to a piezoelectric transformer (1) which is divided in the longitudinal direction (L) into an input region (2) and an output region (3), wherein electrodes (4) and piezoelectric material (5) are alternately stacked in the input region (2) and an alternating voltage can be applied to the electrodes (4) in the input region (2), wherein the output region (3) comprises piezoelectric material (9) which effectuates the build-up of an electrical field when alternating voltage is applied in the input region (2), wherein the piezoelectric transformer (1) has an output-side end face (10) which faces away from the input region (2), and lateral edges (13) which extend in the longitudinal direction (L), and wherein the piezoelectric transformer (1) is designed for ionizing atoms or molecules at the output-side end face (10), thereby avoiding ionization of atoms or molecules at the lateral edges (13).