A cadmium-free, core shell quantum dot, a quantum dot polymer composite, and electronic devices including the quantum dot polymer composite. The core shell quantum dot has an extinction coefficient per gram of greater than or equal to 0.3, an ultraviolet-visible absorption spectrum curve that has a positive differential coefficient value at 450 nm, wherein the core shell quantum dot includes a semiconductor nanocrystal core including indium and phosphorus, and optionally zinc, and a semiconductor nanocrystal shell disposed on the semiconductor nanocrystal core, the shell including zinc, selenium, and sulfur, wherein the core shell quantum dot has a quantum efficiency of greater than or equal to about 80%, and is configured to emit green light upon excitation.