Photoelectric device and substrate thereof

A photoelectric device, comprising a plurality of photoelectric device chips, a substrate, and a first electrode as well as a second electrode disposed on the substrate;

• wherein the substrate comprises:
• a metal base, comprising a die bonding region and a peripheral region surrounding the die bonding region;
• a dielectric layer, disposed on the metal base and located in the peripheral region to define the die bonding region;
• wherein the metal base is formed with at least one groove corresponding to the die bonding region, the at least one groove is filled with a thermally conductive filler, and a filling density of the thermally conductive filler in unit of volume of the metal base is gradually decreased along a direction from a center to an edge of the die bonding region;
• wherein the plurality of photoelectric device chips are secured in the die bonding region of the metal base of the substrate and electrically connected with the first electrode and the second electrode, the first electrode and the second electrode are located in the peripheral region of the metal base.