Electronic properties of the n-type PDI8-CN2 organic semiconductor at the interface with SiO2: addressing the role of adsorbed water molecules by means of optical second-harmonic generation

Year: 2014

Authors: Ciccullo F., Santamaria L., Orabona E., Cassinese A., Maddalena P., Lettieri S.

Autors Affiliation: Institute for Superconductors, Oxides and Innovative Materials, (CNR-SPIN), U.O.S. Napoli, Via Cintia, I-80126 Napoli, Italy; Physics Department, University of Naples Federico II, Via Cintia I-80126 Napoli, Italy

Abstract: We investigate the interfacial electronic properties of N,N’-bis(n-octyl)( 1,7&1,6)-dicyanoperylene-3,4:9,10-bisdicarboximide (PDI8-CN2) organic semiconductor films grown on silicon dioxide (SiO2) by polarization-resolved second harmonic generation optical spectroscopy. The analysis shows a non-uniform distribution of charge carriers in PDI8-CN2, whose spatial profile is affected by hydrophobic passivation of SiO2 surfaces by hexamethyldisilazane. An interpretation model strengthened by photoluminescence analysis is developed, based on the presence of the net charge localized at the SiO2 surface and on consequent charge redistribution in the organic semiconductor. Considerations are expounded suggesting a common and ‘universal’ mechanism for the bias stress effect in p-channel and n-channel organic field-effect transistors, related to proton migration toward SiO2 gate dielectrics.

Journal/Review: NEW JOURNAL OF PHYSICS

Volume: 16      Pages from: 093036  to: 093036

KeyWords: organic semiconductors; interface properties; nonlinear optical spectroscopy; surface optics;
DOI: 10.1088/1367-2630/16/9/093036

Citations: 4
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