The molecular donor 9,9′-ethane-1,2-diylidene-bis(N-methyl9,10- dihydroacridine) (NMA) has been synthesized, and its electronic properties were characterized both in solution using cyclic voltammetry and optical absorption spectroscopy, and at interfaces to metals with photoelectron spectroscopy (PES). The optical energy gap of NMA in solution increases by 0.10eV when the compound is doubly oxidized. On the basis of quantum-chemical calculations, this ipsochromic effect is rationalized by a change in geometry involving a severe torsion of the two acridinium moieties with respect to the central double bond, thus reducing conjugation upon oxidation. PES is reported for NMA deposited on Au(111), Ag(111), and Cu(111) single crystals. A decrease of the sample work function is observed that becomes larger with increasing molecular coverage and clearly exceeds values that would be expected for metal surface electron "push back" alone, confirming the electron donating nature of NMA. The growth mode of NMA on all three surfaces is almost layer-by-layer (Frank-van der Merwe). For tris(8-hydroxyquinoline)aluminum (Alq3) deposited on top of a NMA-modified Au(111) surface, the electron injection barrier (EIB) is reduced by 0.25 eV compared to that on pristine Au(111). Furthermore, the EIB reduction depends linearly on φ of the donor-modified Au(111) surface, adjustable by NMA precoverage. This enables continuous tuning of the EIB in organic electronic devices, in order to optimize device efficiency and performance. © 2009 Wiley-VCH Verlag GmbH&Co. KGaA.

Broeker, B., Blum, R., Beverina, L., Hofmann, O., Sassi, M., Ruffo, R., et al. (2009). A High Molecular Weight Donor for Electron Injection Interlayers on Metal Electrodes. CHEMPHYSCHEM, 10(17), 2947-2954 [10.1002/cphc.200900472].

A High Molecular Weight Donor for Electron Injection Interlayers on Metal Electrodes

BEVERINA, LUCA;SASSI, MAURO;RUFFO, RICCARDO;PAGANI, GIORGIO ALBERTO;
2009

Abstract

The molecular donor 9,9′-ethane-1,2-diylidene-bis(N-methyl9,10- dihydroacridine) (NMA) has been synthesized, and its electronic properties were characterized both in solution using cyclic voltammetry and optical absorption spectroscopy, and at interfaces to metals with photoelectron spectroscopy (PES). The optical energy gap of NMA in solution increases by 0.10eV when the compound is doubly oxidized. On the basis of quantum-chemical calculations, this ipsochromic effect is rationalized by a change in geometry involving a severe torsion of the two acridinium moieties with respect to the central double bond, thus reducing conjugation upon oxidation. PES is reported for NMA deposited on Au(111), Ag(111), and Cu(111) single crystals. A decrease of the sample work function is observed that becomes larger with increasing molecular coverage and clearly exceeds values that would be expected for metal surface electron "push back" alone, confirming the electron donating nature of NMA. The growth mode of NMA on all three surfaces is almost layer-by-layer (Frank-van der Merwe). For tris(8-hydroxyquinoline)aluminum (Alq3) deposited on top of a NMA-modified Au(111) surface, the electron injection barrier (EIB) is reduced by 0.25 eV compared to that on pristine Au(111). Furthermore, the EIB reduction depends linearly on φ of the donor-modified Au(111) surface, adjustable by NMA precoverage. This enables continuous tuning of the EIB in organic electronic devices, in order to optimize device efficiency and performance. © 2009 Wiley-VCH Verlag GmbH&Co. KGaA.
Articolo in rivista - Articolo scientifico
organic electronics
English
2009
10
17
2947
2954
none
Broeker, B., Blum, R., Beverina, L., Hofmann, O., Sassi, M., Ruffo, R., et al. (2009). A High Molecular Weight Donor for Electron Injection Interlayers on Metal Electrodes. CHEMPHYSCHEM, 10(17), 2947-2954 [10.1002/cphc.200900472].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/15954
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