Critical role of electrons in the short lifetime of blue OLEDs
Jaewook Kim, Joonghyuk Kim, Yongjun Kim, Young-Mok Son, Young-Sik Shin, Hye Jin Bae, Ji Whan Kim, Sungho Nam, Yongsik Jung, Hyeonsu Kim, Sungwoo Kang, Yoon-Soo Jung, Kyung-Hoon Lee, Hyeonho Choi, Woo Youn Kim
Abstract
Designing robust blue organic light-emitting diodes is a long-standing challenge in the display industry. The highly energetic states of blue emitters cause various degradation paths, leading to collective luminance drops in a competitive manner. However, a key mechanism of the operational degradation of organic light-emitting diodes has yet to be elucidated. Here, we show that electron-induced degradation reactions play a critical role in the short lifetime of blue organic light-emitting diodes. Our control experiments demonstrate that the operational lifetime of a whole device can only be explained when excitons and electrons exist together. We examine the atomistic mechanisms of the electron-induced degradation reactions by analyzing their energetic profiles using computational methods. Mass spectrometric analysis of aged devices further confirm the key mechanisms. These results provide new insight into rational design of robust blue organic light-emitting diodes.