Display panel, display apparatus, and methods for making the same

A display panel, comprising:

• a plurality of light emitting units each having a light emitting side and a back side;
• a transparent substrate disposed over the light emitting side of the light emitting unit;
• a transparent film disposed over a side of the transparent substrate opposing the light emitting unit,
• wherein:
• the transparent film has an effective refractive index smaller than a refractive index of the transparent substrate;
• the transparent film has a position-dependent refractive index progressively smaller along a light emitting direction from the light emitting unit;
• the transparent film comprises a plurality of sublayers;
• and
• each of the plurality of sublayers has a refractive index progressively smaller than a refractive index of a previous layer that is closer to the light emitting unit;
• wherein the plurality of sublayers comprises:
• a first layer proximal to the light emitting unit and having a first refractive index of 1.4;
• and
• a second layer over the first layer and having a second refractive index of 1.33;
• wherein:
• the first layer comprises MgF2;
• and
• the second layer comprises cryolite.

A method of manufacturing a display panel, comprising:

• forming a plurality of light emitting units and a transparent substrate disposed on a light emitting side of the plurality of light emitting units;
• disposing a transparent film on a side of the transparent substrate that is opposing the plurality of light emitting units, wherein the transparent film comprises a plurality of sublayers;
• wherein each sublayer of the transparent film has a refractive index smaller than that of the transparent substrate, and each sublayer's refractive index is progressively smaller than the previous sublayer ordered in a light-emitting direction;
• and
• forming an anode over the transparent substrate;
• forming a pixel defining layer over the anode;
• forming an organic functional layer over the anode at which the pixel defining layer is formed;
• forming a cathode over the organic functional layer;
• wherein the organic functional layer corresponds to a light-emitting area at the light-emitting side;
• depositing, with a chemical vapor deposition (CVD) process, the transparent film including a MgF2 film sublayer, and a cryolite (n=1.33) film sublayer;
• performing exposure with a variable transmittance mask;
• and
• forming a convex structure over surface of the cryolite film sublayer, having an edge with a plane section forming an angle with the surface plane of the transparent substrate that is equal to or greater than 20 degrees.