Prof. Thomas Wågberg , Department of Physics, Umeå University, Sweden
Self-Assembled PCBM Nanosheets and Nanoribbons: A Facile Route to Electronic Layer-on-Layer Heterostructures
Technische Universität Chemnitz, MAIN, Seminarraum EG , Rosenbergstr. 6 , 09126 Chemnitz
I will discuss on new finding on a peculiar structure called PCBM nanoribbons and PCBM nanosheets. I will particularly present the self-assembly of semicrystalline [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanosheets at the interface between a hydrophobic solvent and water, and show how we utilize this opportunity for the realization of electronically active organic/ organic molecular heterostructures. The self-assembled PCBM nanosheets can feature a lateral size of >1 cm2 and be transferred from the water surface to both hydrophobic and hydrophilic surfaces using facile transfer techniques. We employ a transferred single PCBM nanosheet as the active material in a field-effect transistor (FET) and verify semiconductor function by a measured electron mobility of 1.2 × 10−2 cm2 V−1 s−1 and an on−off ratio of ∼1 × 104. We further fabricate a planar organic/organic heterostructure with the p-type organic semiconductor poly(3-hexylthiophene-2,5-diyl) as the bottom layer and the n-type PCBM nanosheet as the top layer and demonstrate ambipolar FET operation with an electron mobility of 8.7 × 10−4 cm2 V−1 s−1 and a hole mobility of 3.1 × 10−4 cm2 V−1 s−1.
Professor Thomas Wågberg is leading the “Nano for Energy” group at Department of Physics, Umeå University. He also serves as Head of the Physics Department. His research group works on nanomaterial with an emphasis on carbon materials and transition metal nanoparticles for energy applications such as fuel cells and electrolysis but also on sensors for environmental monitoring. The group also focus on fundamental understanding of charge transfer, optical properties and growth properties of nanomaterials. He has co-authored 3 book chapters, about 180 journal papers, served as guest editor and are active in several national research boards.