A color conversion panel that includes a color conversion layer including two or more color conversion regions, and optionally, a partition wall defining the regions of the color conversion layer, and a display device including the color conversion panel. The color conversion region includes a first region corresponding to a first pixel, and the first region includes a first composite including a matrix and a plurality of luminescent nanostructures dispersed in the matrix. The luminescent nanostructures include a first semiconductor nanocrystal including a Group III-V compound and a second semiconductor nanocrystal including a zinc chalcogenide. The Group III-V compound includes indium, phosphorus, and optionally, zinc or gallium, or zinc and gallium, and the zinc chalcogenide includes zinc, selenium, and sulfur. The luminescent nanostructures further include aluminum and chlorine, and a mole ratio of aluminum to sulfur (Al:S) is less than about 0.15:1, a mole ratio of chlorine to sulfur (Cl:S) is less than about 0.1:1, and a mole ratio of sulfur to selenium (S:Se) is greater than or equal to about 2:1. The luminescent nanostructures don not include cadmium.