Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9770050 | Journal of Molecular Structure | 2005 | 5 Pages |
Abstract
Thin films of N,Nâ²-Bis(benzyl)-3,4,9,10-perylenetetracarboxylic diimide (BPTCDI, Fig. 1b) and N,Nâ²-Bis(benzyl)-1,4,5,8-naphthalenetetracarboxylic diimide (BNTCDI, Fig. 1d) were thermally deposited in UHV on 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA, Fig. 1a) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA, Fig. 1c) film surfaces, respectively, in order to form organic-organic interfaces so that molecules constituting the interfacing layers differ by the substituent group. The surface potential and the density of unoccupied electron states (DOUS) located 5-25 eV above the Fermi level (EF) were measured during the film deposition using an incident beam of low-energy electrons according to the total current electron spectroscopy (TCS) method. Analysis of the TCS data allowed us to assign the Ï( band located 5-7.5 eV above EF for all the four films under study and the higher located Ï*1 and Ï*2 bands and the splitting within them. In order to perform the analysis the molecules were hypothetically divided into benzene-like, conjugated and non-conjugated fragments that may individually contribute to the peaks in the DOUS bands. It was shown that a non-conjugated fragment would serve for decreasing of the energy corresponding to the Ï*1 and Ï*2 bands and the sub-bands within them while an addition of a benzene-like fragment would do the opposite. The BPTCDI/PTCDA and BNTCDI/NTCDA interfaces were found non-reacted and a 4.1±0.1 eV work function value for both BPTCDI and BNTCDI films was determined, which is about 0.25 eV lower than the work functions of the PTCDA and the NTCDA films.
Keywords
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Physical Sciences and Engineering
Chemistry
Organic Chemistry
Authors
A.S. Komolov, P.J. Møller, Y.G. Aliaev, E.F. Lazneva, S. Akhremtchik, F.S. Kamounah, J. Mortensen, K. Schaumburg,