AVS 51st International Symposium
    Organic Films and Devices Thursday Sessions
       Session OF+EM-ThA

Paper OF+EM-ThA5
Molecular N-Type Doping of NTCDA by Pyronin B

Thursday, November 18, 2004, 3:20 pm, Room 304C

Session: Molecular and Organic Films and Devices - Optoelectronic
Presenter: C.K. Chan, Princeton University
Authors: C.K. Chan, Princeton University
A. Kahn, Princeton University
Correspondent: Click to Email
Molecular n-type doping of 1,4,5,8-naphthalene tetracarboxylic dianhydride (NTCDA) by pyronin B (PyB) is observed using ultraviolet photoemission spectroscopy (UPS) and inverse photoemission spectroscopy (IPES). The leuco form of the dopant molecule is prepared in situ by heating the stable PyB chloride salt until sublimation@footnote 1@. UPS of the neat PyB film shows that the highest occupied molecular orbital (HOMO) of the material is 5.69eV below the vacuum level (E@sub vac@), whereas the lowest unoccupied molecular orbital (LUMO) of NTCDA is at 4.08eV below E@sub vac@, as determined by IPES. Despite this relatively large energy difference between donor and electron transport states, the deposition of small amounts (<2Å) of PyB on pristine NTCDA films leads to a shift of the HOMO away from the Fermi-level by nearly 0.20eV, indicative of n-type doping of NTCDA by PyB and in agreement with the results of Werner et al.@footnote 1@. Interface and bulk energy levels of co-evaporated films show similarly efficient doping. Current-voltage measurements on doped NTCDA diode devices will also be presented. @FootnoteText@ @footnote 1@ A. G. Werner, F. Li, K. Harada, M. Pfeiffer, T. Fritz, and K. Leo, Appl. Phys. Lett. 82, 4495 (2003).