Self-Assembled PCBM Nanosheets: A Facile Route to Electronic Layer-on-Layer Heterostructures

We report on the self-assembly of semicrystalline [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) nanosheets at the interface between a hydrophobic solvent and water, and 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 cm 2 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 cm 2 V -1 s -1 and an on-off ratio of ∼1 × 10 4 . 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 cm 2 V -1 s -1 and a hole mobility of 3.1 × 10 -4 cm 2 V -1 s -1 .