Photoconduction and magnetic field effect on photoconduction in hole-transporting star-burst amine (m-MTDATA) films

• Published in: Organic electronics Vol. 21; pp. 54 - 65
• Main Authors: Pelczarski, Daniel, Grygiel, Piotr, Miśnik, Maciej, Stampor, Waldemar
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2015
• Subjects: Charge photogeneration; Magnetic effects; Photoconduction; Starburst amines; Starburst amines; Photoconduction; Magnetic effects; Charge photogeneration
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2015.02.020

[Display omitted] •We have studied photocurrents (PCs) in vacuum deposited m-MTDATA films.•The PCs are ascribed to exciton dissociation at Al anode or in the bulk of the film.•The PC mechanism is rationalized in terms of the Onsager theory.•We have observed the positive magnetic field effect (MPC) on the bulk PC component.•The MPC effect is due to hyperfine- and fine-field structure modulation. Photoconduction and magnetic field effect on photoconduction have been investigated as a function of electric field strength, excitation light intensity and wavelength in vacuum evaporated films of m-MTDATA (4,4′,4″-tris(N-(3-methylphenyl)-N-phenylylamino) triphenylamine), the starburst amine commonly used as hole-transporting material in organic light-emitting diodes. The photocurrent is found to be generated by the singlet exciton dissociation at the illuminated Al anode/m-MTDATA interface in accordance with the 1-D Onsager mechanism and in the bulk of the sample in terms of the 3-D Onsager model of e–h pair separation. The surface component of photocurrent is magnetic field independent whereas the bulk-generated photocurrent is influenced by external magnetic field of the hyperfine coupling (HFC) as well as fine structure modulation (FSM) scales.