Quantum dots, composites, and device including the same

A quantum dot comprising

• a seed comprising a first semiconductor nanocrystal,
• a quantum well layer disposed on the seed, and
• a shell disposed on the quantum well layer, the shell comprising a second semiconductor nanocrystal,
• wherein the quantum dot does not comprise cadmium,
• wherein the first semiconductor nanocrystal comprises a first zinc chalcogenide,
• wherein the second semiconductor nanocrystal comprises a second zinc chalcogenide,
• wherein the quantum well layer comprises an alloy semiconductor nanocrystal comprising indium, phosphorus, and gallium,
• wherein a bandgap energy of the alloy semiconductor nanocrystal is less than a bandgap energy of the first semiconductor nanocrystal and less than a bandgap energy of the second semiconductor nanocrystal, and
• wherein in the quantum dot, a mole ratio of gallium with respect to a sum of indium and gallium is greater than or equal to about 0.01:1 and less than or equal to about 0.5:1.