Tuning of metal work functions with self-assembled monolayers
| Autor: | de Boer, B, Hadipour, A, Foekema, R, van Woudenbergh, T, Mandoc, MM, Mihailetchi, VD, Blom, PWM, Heremans, PL, Muccini, M, Hofstraat, H |
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| Rok vydání: | 2004 |
| Předmět: |
Materials science
LEDs photovoltaic cells Analytical chemistry work function tuning CHARGE INJECTION interfaces DISULFIDES DEPENDENCE Monolayer OLED WETTING PROPERTIES MOLECULAR PACKING ELECTRONIC DEVICES Work function GOLD Ohmic contact ATOMIC-FORCE MICROSCOPY Organic electronics perfluorinated alkanethiols business.industry SURFACES Self-assembled monolayer self-assembly SAM ALKANETHIOLS Electrode Optoelectronics Self-assembly business dipole |
| Zdroj: | ORGANIC OPTOELECTRONICS AND PHOTONICS, 18-25 STARTPAGE=18;ENDPAGE=25;TITLE=ORGANIC OPTOELECTRONICS AND PHOTONICS |
| ISSN: | 0277-786X |
| DOI: | 10.1117/12.546046 |
| Popis: | Tuning the work functions of metals was demonstrated by chemically modifying the metal surface through the formation of chemisorbed self-assembled monolayers (SAMs) derived from 1H,1H,2H,2H-perfluorinated alkanethiols and hexadecanethiol. The ordering inherent in the SAMs creates an effective, molecular dipole at the metal/SAM interface, which increased the work function of Ag (Phi(Ag) similar to 4.4 eV) to 5.5 eV (DeltaPhi similar to 1.1 eV) for 1H,1H,2H,2H-perfluorinated alkanethiols. Hexadecanethiol on the other hand shifted Phi(Ag) toward 3.8 eV (DeltaPhi similar to 0.6 eV) and raised the energy barrier for hole injection. These SAMs on Au were less efficient. 1H,1H,2H,2H-perfluorodecanethiol raised Phi(Ag) (4.9 eV) by 0.5 eV to 5.4 eV, whereas hexadecanethiol decreased DeltaPhi by only 0.1 eV. These chemically modified electrodes were applied in the fabrication of pLEDs and the hole conduction of MEH-PPV was investigated. An ohmic contact for hole injection between a silver electrode functionalized with the perfluorinated SAMs, and MEH-PPV with a HOMO of 5.2 eV was established. Conversely, a silver electrode modified with a SAM of hexadecanethiol lowered Phi(Ag) to 3.8 eV, creating an efficient energy barrier for hole injection. This method demonstrates a simple and attractive approach to modify and improve metal/organic contacts in organic electronic devices like LEDs and photovoltaic cells. |
| Databáze: | OpenAIRE |
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