Hosono Hideo, Kim Junghwan, Toda Yoshitake, Kamiya Toshio, Watanabe Satoru
Materials Research Center for Element Strategy, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan;
Laboratory for Frontier Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan.
Proc Natl Acad Sci U S A. 2017 Jan 10;114(2):233-238. doi: 10.1073/pnas.1617186114. Epub 2016 Dec 27.
Efficient electron transfer between a cathode and an active organic layer is one key to realizing high-performance organic devices, which require electron injection/transport materials with very low work functions. We developed two wide-bandgap amorphous (a-) oxide semiconductors, a-calcium aluminate electride (a-C12A7:e) and a-zinc silicate (a-ZSO). A-ZSO exhibits a low work function of 3.5 eV and high electron mobility of 1 cm/(V · s); furthermore, it also forms an ohmic contact with not only conventional cathode materials but also anode materials. A-C12A7:e has an exceptionally low work function of 3.0 eV and is used to enhance the electron injection property from a-ZSO to an emission layer. The inverted electron-only and organic light-emitting diode (OLED) devices fabricated with these two materials exhibit excellent performance compared with the normal type with LiF/Al. This approach provides a solution to the problem of fabricating oxide thin-film transistor-driven OLEDs with both large size and high stability.
阴极与活性有机层之间的高效电子转移是实现高性能有机器件的关键之一，这类器件需要具有极低功函数的电子注入/传输材料。我们开发了两种宽带隙非晶（a-）氧化物半导体，即a-铝酸钙电子化物（a-C12A7:e）和a-硅酸锌（a-ZSO）。A-ZSO的功函数低至3.5 eV，电子迁移率高达1 cm/(V·s)；此外，它不仅与传统阴极材料，还与阳极材料形成欧姆接触。A-C12A7:e的功函数极低，为3.0 eV，用于增强从a-ZSO到发射层的电子注入性能。与采用LiF/Al的常规类型相比，用这两种材料制造的倒置单电子和有机发光二极管（OLED）器件表现出优异的性能。这种方法为制造兼具大尺寸和高稳定性的氧化物薄膜晶体管驱动OLED的问题提供了解决方案。
