A quantum dot composite comprising: a matrix and a plurality of quantum dots dispersed in the matrix, wherein the plurality of the quantum dots comprises a semiconductor nanocrystal core including indium and phosphorous, a semiconductor nanocrystal shell disposed on the semiconductor nanocrystal core, and the semiconductor nanocrystal shell including zinc, selenium, and sulfur. The arithmetic size of the plurality of the quantum dots is greater than or equal to about 8 nm, wherein the quantum dot composite is configured to emit red light, and wherein when the quantum dot composite is irradiated with light of a wavelength of from about 450 nm to about 470 nm for a time period of less than or equal to about 500 hours, a luminance increase of the quantum dot composite is less than or equal to about 1.2% of an initial luminance of the quantum dot composite.