BACKGROUND OF INVENTION

Field of Invention

The present invention relates to a display, and more particularly to a large-sized high-resolution display and a method of preparing the same.

Description of Prior Art

At present, a small-sized active-matrix organic light-emitting diode (AMOLED) generally adopts a red-green-blue organic light-emitting diode (RGBOLED) and a fine metal mask (FMM) process, which has a non-obvious phenomenon of IR drop. A large-sized AMOLED panel adopts a white organic light-emitting diode with a color filter (WOLED+CF) process, which needs a cathode having high transparency for top emission and high resolution, so the film thickness must be very thin, which leads to a large impedance. Based on constraints of the current material and design, the IR drop problem occurs between a center of a display area and its peripheral during operation. For a target of mass production, especially G8.5 or above, a design of introduction of an auxiliary electrode is required to provide additional assistance to areas of large IP drop, so that display of the entire screen is uniform and stable during operation. At present, a main solution is to fabricate the auxiliary electrode into an inverted trapezoidal spacer column, which is high in cost and complicated in process, and a backboard of an electroluminescence/ink-jet printing organic light-emitting diode (EL/IJP-OLED) is more difficult to implement, additionally requiring a contact via, which is unfavorable to the design of a circuit and the backboard of high resolution (pixels per inch, PPI).

In order to solve the above problems of the conventional display, there is an urgent need to develop a large-sized and high-resolution display.

SUMMARY OF INVENTION

In view of the above, the present invention provides a display that utilizes a design of an auxiliary electrode of an organic light-emitting diode (OLED) panel made by large-scale evaporation coating or printing, wherein by changing the backboard design, during the anode process, the auxiliary source trace is prepared in advance, such that the trace is located at a bottom of a pixel definition layer (PDL). During the PDL layer process, an opening is formed along a lengthwise direction of a sub-pixel, and electrical conductors having protruding portions are formed to connect with auxiliary source traces. A distance of the electrical conductors having the protruding portions higher than the PDL is determined according to thicknesses of an electroluminescence (EL) layer and a cathode, and sidewalls of the electrical conductors having the protruding portions are designed to be steep, so that material of the electroluminescent layer is naturally broken between a top and a bottom of the electrical conductors. As such, the cathode material can be evaporated at the broken positions to achieve electrical connections to the sidewalls of the electrical conductors. Since the electrical conductors along a long axis of the sub-pixel is large, connection areas of the cathodes and the electrical conductors become two-dimensional, and are greatly enlarged, thereby improving the poor performance of a conventional point connection to auxiliary electrode. In addition, the auxiliary electrode design proposed by the present invention occupies no extra space, that is, the problem of IR drop of the active-matrix organic light-emitting diode (AMOLED) panel is solved while increasing the design space of the light-emitting area during illuminating the top backboard.

Accordingly, an embodiment of the present invention provides a display including: a thin film transistor substrate including a plurality of thin film transistors; a planarization layer disposed on the thin film transistor substrate; a plurality of anodes and a plurality of auxiliary source traces disposed on the planarization layer, wherein the plurality of anodes are electrically connected to the plurality of thin film transistors through the planarization layer; a pixel definition layer disposed on the plurality of anodes, the plurality of auxiliary source traces, and the planarization layer not covered by the plurality of anodes and the plurality of auxiliary source traces, wherein the pixel definition layer has a plurality of first openings respectively corresponding to and exposing the plurality of auxiliary source traces, and the pixel definition layer has a plurality of second openings respectively corresponding to and exposing the plurality of anodes; a plurality of electrical conductors filled in the plurality of first openings and on a portion of the pixel definition layer around the plurality of first openings, wherein the plurality of electrical conductors have a plurality of protruding portions higher than the pixel definition layer; an electroluminescent layer covering an upper surface of the electrical conductors and a sidewall and a bottom of the plurality of second openings; and a plurality of cathodes covering the electroluminescent layer and electrically connected to sidewalls of the plurality of electrical conductors respectively.

According to another embodiment of the present invention, the present invention also provides a method of preparing a display, including:

S10, providing a thin film transistor substrate, wherein the thin film transistor substrate includes a plurality of thin film transistors;

S20, forming a planarization layer on the thin film transistor substrate;

S30, forming a plurality of anodes and a plurality of auxiliary source traces on a portion of the planarization layer, wherein the plurality of anodes are electrically connected to the plurality of thin film transistors through the planarization layer;

S40, forming a pixel definition layer on the plurality of anodes, the plurality of auxiliary source traces, and the planarization layer not covered by the plurality of anodes and the plurality of auxiliary source traces, wherein the pixel definition layer has a plurality of first openings respectively corresponding to and exposing the plurality of auxiliary source traces, and the pixel definition layer has a plurality of second openings respectively corresponding to and exposing the plurality of anodes;

S50, forming a plurality of electrical conductors filled in the plurality of first openings and on a portion of the pixel definition layer around the plurality of first openings, wherein the plurality of electrical conductors have a plurality of protruding portions higher than the pixel definition layer;

S60, forming an electroluminescent layer on an upper surface of the electrical conductor and a sidewall and a bottom of the plurality of second openings; and

S70, forming a plurality of cathodes on the electroluminescent layer and electrically connected to sidewalls of the plurality of electrical conductors respectively.

In an embodiment of the invention, in the step S60, forming the electroluminescent layer includes evaporation coating, and material of the electroluminescent layer is naturally broken at sidewalls of the protruding portions to form broken positions which expose the sidewalls of the protruding portions.

In an embodiment of the invention, in the step S70, forming the plurality of cathodes includes: performing evaporation coating at a specific angle according to the included angle to achieve electrical connections of the plurality of cathodes to the sidewalls of the protruding portions at the broken positions.

In an embodiment of the invention, the plurality of electrical conductors include a metallic or organic electrically conductive material, and the electroluminescent layer includes an organic material.

In an embodiment of the invention, the plurality of electrical conductors are higher than upper surfaces of the plurality of cathodes.

In an embodiment of the invention, an included angle between a sidewall of each of the plurality of protruding portions and an upper surface of the pixel definition layer is less than or equal to 90 degrees.

In an embodiment of the invention, each of the plurality of protruding portions has a rectangular shape, an inverted trapezoidal shape, or an irregular shape wide at top and narrow at bottom.

In an embodiment of the invention, the sidewalls of the plurality of protruding portions are flat or irregularly shaped surfaces.

In an embodiment of the invention, the electroluminescent layer is configured to emit white light.

The present invention provides a display that utilizes a design of an auxiliary electrode of an organic light-emitting diode (OLED) panel made by large-scale evaporation coating or printing, wherein by changing the backboard design, during the anode process, the auxiliary source trace is prepared in advance such that the trace is located at a bottom of a pixel definition layer (PDL). During the PDL layer process, an opening is formed along a lengthwise direction of a sub-pixel, and electrical conductors having protruding portions are formed to connect with auxiliary source traces. A distance of the electrical conductors having the protruding portions higher than the PDL is determined according to thicknesses of an electroluminescence (EL) layer and a cathode, and sidewalls of the electrical conductors having the protruding portions are designed to be steep, so that material of the electroluminescent layer is naturally broken between a top and a bottom of the electrical conductors. As such, the cathode material can be evaporated at the broken positions to achieve electrical connections to the sidewalls of the electrical conductors. Since the electrical conductors along a long axis of the sub-pixel is large, connection areas of the cathodes and the electrical conductors become two-dimensional, and are greatly enlarged, thereby improving the poor performance of a conventional point connection to auxiliary electrode. In addition, the auxiliary electrode design proposed by the present invention occupies no extra space, that is, the problem of IR drop of the active-matrix organic light-emitting diode (AMOLED) panel is solved while increasing the design space of the light-emitting area during illuminating the top backboard.

