Satoh Naoya, Tanno Tsubasa, Kitabayashi Takuya, Kiba Takayuki, Kawamura Midori, Abe Yoshio
Department of Materials Science and Engineering, Kitami Institute of Technology, Kitami 090-8507, Japan.
ACS Omega. 2022 May 18;7(21):17861-17867. doi: 10.1021/acsomega.2c01128. eCollection 2022 May 31.
Organic light-emitting diodes (OLEDs) have been widely used, particularly in display applications. OLEDs are easily degraded without stringent encapsulation owing to their susceptibility to water vapor and oxygen. Therefore, establishing an effective protection method for these devices is essential. In this study, we demonstrate the device protection performance and improvement in color purity by introducing CaF/ZnS multilayered films on a top-emitting inverted-type OLED (iOLED), which was originally intended to act as a distributed Bragg reflector (DBR). To test the protection performance of each dielectric layer, conventional bottom-emitting OLEDs (cOLEDs) with and without single layers of CaF and ZnS were investigated for comparison. All OLEDs were stored in an atmosphere without stringent encapsulation, such as a cover glass. The luminescence area of cOLEDs without the dielectric film decreased by more than 90% after 3 days of fabrication. In contrast, the dark-spot formation was moderated after the same period for the dielectric single-layer deposited cOLEDs. Notably, the iOLED with DBR completely preserved the emitting area even after 2 months of fabrication. This suggests that DBR acted as a protective film for the organic layer, whereas the inverted structure also contributed to reducing the degradation of air- and moisture-sensitive materials.
有机发光二极管（OLED）已被广泛应用，尤其是在显示应用中。由于OLED对水蒸气和氧气敏感，若无严格封装，它们很容易降解。因此，为这些器件建立一种有效的保护方法至关重要。在本研究中，我们通过在顶部发射倒置型OLED（iOLED）上引入CaF/ZnS多层膜来展示器件的保护性能和色纯度的提高，该iOLED原本用作分布式布拉格反射器（DBR）。为了测试每个介电层的保护性能，研究了有无单层CaF和ZnS的传统底部发射OLED（cOLED）进行比较。所有OLED都存储在没有严格封装的大气环境中，例如覆盖玻璃下。制备后3天，没有介电膜的cOLED的发光面积减少了90%以上。相比之下，对于沉积了介电单层的cOLED，在同一时期后暗斑形成得到了缓解。值得注意的是，带有DBR的iOLED即使在制备后2个月仍完全保留了发光面积。这表明DBR起到了有机层保护膜的作用，而倒置结构也有助于减少对空气和湿气敏感材料的降解。
