Quantum dot composite material, preparation method, and semiconductor device

A method for preparing a quantum dot (QD) composite material, comprising:

• synthesizing a first compound at a predetermined position;
• synthesizing a second compound on a surface of the first compound, wherein the second compound and the first compound have a same alloy composition, or have different alloy compositions;
• and
• forming the QD composite material through a cation exchange reaction between the first compound and the second compound, wherein a light-emission peak wavelength of the QD composite material experiences a blue-shift and then remains unchanged, wherein:
• the QD composite material comprising at least two QD structural units arranged sequentially along a radial direction;
• the QD composite material includes a type A3 QD structural unit and a type A4 QD structural unit, wherein the type A3 QD structural units has a gradient alloy composition structure with an energy level width increasing along the radial direction toward a surface, and the type A4 QD structural unit has a homogeneous alloy composition structure;
• an inner part of the QD composite material includes one or more QD structural units having a gradient alloy composition structure, and energy levels in adjacent QD structural units having gradient alloy composition structures are continuous;
• and
• the QD composite material includes one or more QD structural units having a homogeneous alloy composition structure in a region close to the surface.

A semiconductor device comprising a quantum dot (QD) composite material, the QD composite material comprising at least two QD structural units arranged sequentially along a radial direction, wherein:

• the QD composite material includes a type A3 QD structural unit and a type A4 QD structural unit, wherein the type A3 QD structural units has a gradient alloy composition structure with an energy level width increasing along the radial direction toward a surface, and the type A4 QD structural unit has a homogeneous alloy composition structure;
• an inner part of the QD composite material includes one or more QD structural units having a gradient alloy composition structure, and energy levels in adjacent QD structural units having gradient alloy composition structures are continuous;
• and
• the QD composite material may include one or more QD structural units having a homogeneous alloy composition structure in a region close to the surface.