A light-emitting device having a first light-emitting layer with a first quantum dot having a first core part and a first shell part. The first shell part has a surface coated with a surfactant, and the first shell part has a thickness of 3 to 5 ML based on the constituent molecule of the first shell part. The light-emitting device also can have second light-emitting layer with a second quantum dot having a second core part and a second shell part. The second shell part has a surface coated with two types of hole-transporting and electron-transporting surfactants, and the second shell part has a thickness of less than 3 ML based on the constituent molecule of the second shell part.