Colloidal II-VI nanocrystals have garnered significant research attention in nonlinear optical applications due to their low-cost synthesis, photophysical tunability, and ease of device integration. Herein, we report that dual-type II CdSe/CdTe/CdSe colloidal quantum wells (CQWs) with core/crown/crown structures achieve remarkable nonlinear optical limiting capabilities driven by an exceptionally large nonlinear absorption coefficient. Open aperture