As we chose the materials that their work functions closed to the HOMO of NPB, they could be used for improving the hole-injection efficiency and lowering the driving voltage.

• 第二部分为探讨以真空热蒸镀的方式，所制成单层金属氧化物结构、光电特性，并辅助说明电荷载子在元件中如何注入、传输等机制。