A quantum dot including a core and a shell disposed on the core wherein one of the core and the shell includes a first semiconductor nanocrystal including zinc and sulfur and the other of the core and the shell includes a second semiconductor nanocrystal having a different composition from the first semiconductor nanocrystal, the first semiconductor nanocrystal further includes a metal and a halogen configured to act as a Lewis acid in a halide form, an amount of the metal is greater than or equal to about 10 mole percent (mol %) based on a total number of moles of sulfur, and an amount of the halogen is greater than or equal to about 10 mol % based on a total number of moles of sulfur, a method of producing the same, and a composite and an electronic device including the same.