Photoemission spectroscopy study on interfacial energy level alignments in tandem organic light-emitting diodes

Qing-Dong Ou, Chi Li, Yan-Qing Li, Jian-Xin Tang

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9 Citations (Scopus)


Organic light-emitting diodes (OLEDs) using a tandem structure offer a highly attractive option for the applications of next-generation flat panel displays and solid-state lighting due to the extremely high brightness and efficiency along with the long operational lifetime. In general, reliable information about interface energetics of the charge generation layers (CGLs), which plays the central role in charge generation and carrier injection into the stacked emission units, is highly desirable and advantageous for interface engineering and the performance optimization of tandem OLEDs. In this review, our recent studies on tandem OLEDs are overviewed, especially from interface energetics perspective via photoemission spectroscopy. The electronic structures of various transition metal oxide (TMO)-based CGLs and their role in charge generation process are reviewed, addressing the n-type doping impact of organic layers in CGLs, thermal annealing-induced oxygen vacancy in TMOs, and the interfacial stability of CGLs on the device operational lifetime. The resulting energy level alignments are summarized in correspondence with tandem OLED performance.

Original languageEnglish
Pages (from-to)186-195
Number of pages10
JournalJournal of Electron Spectroscopy and Related Phenomena
Issue numberPart A
Publication statusPublished - 1 Oct 2015
Externally publishedYes


  • Charge generation layer
  • Energy level alignment
  • n-Type doping
  • Photoemission spectroscopy
  • Tandem OLEDs
  • Transition metal oxides

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