OLED

Organic light emitting diode (OLED), also known as organic electroluminescence display or organic electroluminescence (EL) diode, is a flat light-emitting technology made by placing a series of organic thin films between two conductors. When an electric current is applied, OLED can generate a bright light, and the intensity of the light is proportional to the injected current. OLED does not require a backlight, which creates images and emits its own light. Therefore, OLED has the characteristics of lightness, thinness, and power-saving, making it suitable for TV screens, computer displays, portable system displays to display information.

OLED Classification

There are many types of OLEDs, and classification methods are diverse. OLEDs can be classified according to driving methods, material types, and device structures, as shown below.

• According to the driving method, OLED is divided into active and passive OLEDs. The former is generally an active-matrix OLED (AMOLED) used in high-resolution products, while the latter is a passive-matrix OLED (PMOLED) used in displays with relatively small sizes.
• According to the different materials constituting OLEDs, OLEDs can be divided into small molecule OLEDs and polymer OLEDs. The main difference between the two devices lies in the fabrication process.
• According to the device structure, OLEDs can be divided into four types: single-layer, double-layer, three-layer, and multilayer OLEDs.

Applications of Photoresists in OLED

Regardless of the type of OLED being manufactured, photoresist plays an important role in its fabrication. The fabrication of some OLED components requires the use of photoresist through photolithography, including organic luminescent layers, encapsulation structures, electrodes, and transparent conducting films.

• Organic luminescent layers

The organic luminescent layer in OLED is a key component to realize photoelectric conversion. Photoresist is used for luminescent layer patterning. It is coated on the substrate and defines the pattern of the light-emitting layer through a photomask. As a result of development and removal, the pattern and structure of the organic luminescent layer are obtained, which ensures its high resolution.

• Encapsulation structures

OLEDs require encapsulation to protect the organic luminescent layer and circuitry. Photoresists function as adhesive layers and patterning layers during encapsulation structure fabrication. Coating a photoresist and transferring the pattern of the photoresist to the encapsulation material through photolithography makes the adhesive layer and the pattern of the encapsulation structure are formed. The application of photoresist ensures accuracy and good adhesion of the encapsulation structure.

• Electrodes

Electrodes in OLEDs are used to inject current and collect charges, which are key components to achieve electron and photon conversion. A photoresist layer in electrode fabrication is necessary. Photoresist is coated on the electrode material, and the pattern on the photomask is transferred to the electrode through a series of photolithography steps. Finally, unnecessary photoresist is removed to obtain electrodes with a specific pattern.

• Transparent conducting films

Transparent conducting film is an important part of OLED, which not only provides electrical conductivity, but also provides light transmission. Commonly used materials are indium tin oxide (ITO), transparent conductive oxide (TCO), and conductive polymers, of which TCO requires good solar wavelength transmittance. Photoresist plays a key role in transparent conducting film preparation. By transferring a photomask pattern to a transparent conductive material, a transparent conducting film with a specific pattern can be obtained, and it can be applied to the electrode of an OLED.

Alfa Chemistry offers a wide range of photoresists for flat panel displays. Our customer services representatives are available 24 hours a day, from Monday to Sunday. Please feel free to contact us with any concerns. We will be happy to assist you in any way we can.

CONTACT US

Please kindly note that our products and services are for research use only.