A quantum dot device including an anode; a cathode disposed substantially opposite to the anode; a hole injection layer disposed on the anode between the anode and the cathode; a hole transport layer disposed on the hole injection layer between the hole injection layer and the cathode; and a quantum dot layer disposed on the hole transport layer between the hole transport layer and the cathode, wherein the quantum dot layer includes a plurality of quantum dots, wherein the hole transport layer includes a hole transport material and an electron transport material, and wherein a lowest unoccupied molecular orbital (LUMO) energy level of the electron transport material and a lowest unoccupied molecular orbital (LUMO) energy level of the quantum dot layer is about 0.5 electron volts or less.