Heteroatom Bay-Annulated Perylene Bisimides: New Materials for Organic Field Effect Transistors

We report the synthesis of bay-annulated (N, S, and Se) perylene bisimides (PBIs) and their structural, thermal, photophysical, electrochemical, and morphological characterization. In addition, their application in organic field effect transistors (OFETs) is demonstrated. All the PBIs except PBI-Se exhibited bright emission in solutions and thin films. Planar molecular structure, variation of the HOMO-LUMO levels, and the energy gaps were evaluated with the help of Gaussian simulation. Morphology of all the synthesized PBIs has been investigated with the aid of polarizing optical microscopy and atomic force microscopy (AFM). AFM topographical images exhibited surface roughness value ranging from 1.98 to 3.52 nm. Powder X-ray diffraction data revealed the lamellar packing of these molecules in the thermally evaporated thin films. It has been witnessed that the OFET device with top-contact bottom-gate configuration, where the PBI-S served as the semiconducting layer, exhibited the highest electron mobility (mu = 4.40 X 10(-3) cm(2) V-1 s(-1)) in comparison to PBI-N and PBI-Se, due to the better thin film growth mechanism. These materials are promising from the viewpoint of n-type materials that can be utilized in organic electronics.