Anionic and cationic influence on the nonlocal nonlinear optical response of ionic liquids

► We investigated the nonlocal nonlinearity of ionic liquids. ► Large values of thermal nonlinear response and degree of nonlocality were obtained. ► Structures with Tf2N− as the anion present lower nonlinear response. ► Changing the cationic part does not modify significantly the thermal nonlinearity. ► Ionic liquids can be exploited as nonlinear media with large nonlocal character.