Compared to liquid crystal display (LCD), organic light-emitting diode (OLED) device may have less energy consumption but high brightness and high response speed due to its self-light-emitting capability. In addition, OLED device may also be used to fabricate flexible display. As such, OLED has become a mainstream device in the field of display technology.
The essential basis for OLED products to have a wide range of applications is that the device can be operated durably, stably, and continuously. However, after a certain period of time of operation, black spots may appear in the light-emitting components of the OLED device while gas bubbles may also appear in the electrodes, causing device failure. In addition to thermal effect of the organic function layer in the device, black spots and gas bubbles may occur due to chemical reactions of the cathode and the organic function layer of the device with water vapor and oxygen permeated from outside of the device.
In order to improve the lifetime of OLED products, packaging process may be required so that the device may be isolated from external water vapor and oxygen. However, in current practice, the barrier layer used for packaging is usually made of inorganic material, which may still have some problems. For example, the barrier layer may be formed by multiple thin-film layers made of inorganic materials. In such a barrier layer, the internal stress after the deposition of the films may be relatively large, thus the reliability of the product may be low. In addition, the deposition method of inorganic material may inevitably induce defects such as little cracks, impurities, etc., which may further affect the packaging results. Moreover, an overlapping structure with multiple alternatingly-stacked organic and inorganic layers is commonly used in current packaging structures to reduce the stress in each inorganic layer. However, such an overlapping multiple-layer structure usually needs to have 7 or more layers in order to effectively relieve the stress, thus the manufacturing cost may increase while the fabrication process may become more complicated.
The disclosed packaging structures, display devices, and fabrication methods are directed to solve one or more problems set forth above and other problems in the art.