Role of solution-processable polyethylenimine electrode interlayer in fabricating air-stable polymer light-emitting diodes

Ming Wei Lin, Yu Chun Lin, Asslbekov Rauan, Ten-Chin Wen, Yao Jane Hsu, Tzung-Fang Guo

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

This work investigates the mechanisms for the enhanced injection of electrons from a solution-processable polyethyleneimine (PEI) interlayer/aluminum (Al), silver (Ag), or gold (Au) electrodes in phenyl-substituted poly(para-phenylene vinylene) (PPV) copolymer (SY-PPV)-based polymer light-emitting diodes (PLEDs). The bilayer cathode significantly enhances electron injection and device performance, and is comparable to that of PLEDs using low work function metals, such as calcium (Ca) or lithium fluoride (LiF)/Al as the cathode. The functions of the PEI interlayer are characterized by current density-light intensity-voltage (J-L-V) and photovoltaic measurements, X-ray photoelectron spectroscopy, and ultraviolet photoelectron spectroscopy. The thin PEI film forms a dipole layer to shift the vacuum level of the electroluminescent polymer and decrease the barrier height for electron injection. The existing dipoles are correlated with a large numbers of amino groups in the PEI polymer. As a result, the PLEDs with PEI/Al, PEI/Ag, and PEI/Au bilayer cathodes exhibit markedly enhanced performances. The application of air-stable metals as the cathode allows flexibility in the design of device cathode structures for real applications.

Original languageEnglish
Pages (from-to)935-941
Number of pages7
JournalIsrael Journal of Chemistry
Volume54
Issue number7
DOIs
Publication statusPublished - 2014 Jan 1

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

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