PMOLED (Passive Matrix OLED) is a kind of OLED display technology, which uses the principle of passive matrix to control pixels, which is different from AMOLED (Active Matrix OLED). Compared with AMOLED, the manufacturing process of PMOLED is simpler, but the biggest weakness is that it cannot produce high-resolution and large-size screens.

 

The process of making PMOLED can be roughly divided into the following steps:

1. Substrate preparation: Select a substrate suitable for PMOLED production, common materials such as glass and plastic.

2. Fabrication of the photoresist layer: first coat a layer of photoresist layer on the substrate, this step is to prepare for the fabrication of the pixel structure.

3. Metal electrode production: Printing metal electrodes can be made by different production methods such as electroplating and etching. The function of the metal electrodes is to apply an electric field on the pixel unit.

4. Evaporation of organic light-emitting materials: attach a layer of organic light-emitting materials to the metal electrodes. The layer of organic luminescent material contains fluorescent dye and fluorescent group. When electrons flow through these materials, they fluoresce and emit light. This is a crucial step for PMOLEDs to work.

5. Secondary cathode sealing: Since organic light-emitting materials are extremely sensitive to air, they are easily oxidized in air and lose their charge transport properties, resulting in screen failure. Therefore, after OLEDs are made, they must be covered with a layer of transparent materials. The material of this layer must also be sealed so that the organic light-emitting material does not come into contact with the air. Therefore, adding a parafilm to the OLED is an essential step.

6. Positive electrode production: Add a layer of transparent anode on top of the organic light-emitting material as the electrified field plate, and its production method is similar to that of metal electrodes.

 

The above are the main steps in making PMOLED, these steps are usually operated in a clean room or similar environment to keep the material pure and produce the highest quality device with the smallest defects.

Since the manufacturing process of PMOLED is relatively simple, its cost is lower than that of AMOLED. However, PMOLED has limited resolution and small area, which limits its application.