Organic field effect transistors based on 5,10,15,20-tetrakis(4-pentyloxyphenyl)porphyrin single crystal

Diffusion of methanol into the chloroform solution of metal free 5,10,15,20-tetrakis(4-pentyloxyphenyl)porphyrin H2TPOPP yields large single crystals with length as long as 1.5 mm, which allow the fabrication of single crystal-based organic field effect transistors (OFETs). These single crystal-based devices were revealed to exhibit relatively good OFET performance with the carrier mobility for hole of 0.0018 cm2 V−1 s−1 and current modulation of 104. In addition to confirming the tetrappyrole nature, single crystal X-ray diffraction analysis also reveals the planar two-dimensional supramolecular structures formed via porphyrin molecules in the head-to-tail manner through C–H⋯O interaction between oxygen atom and pyrrole hydrogen atom as well as p(O)–π(phenyl) interaction between the meso-attached phenyloxy groups of neighboring porphyrin molecules in the single crystal. This results in effective intermolecular interaction due to the significant participation of phenyloxy groups to the HOMO of the central porphyrin core as revealed by density functional theory (DFT) analysis and in turn is responsible for the relatively good OFET performance in terms of carrier mobility for hole in the direction parallel to the aromatic porphyrin ring. Density functional theory (DFT) calculation also reproduces the experimentally revealed carrier mobility for hole in the single crystal of H2TPOPP. The present work, representing our continuous efforts in understanding the relationship between molecular structure, crystal packing, and OFET performance of tetrapyrrole organic semiconductors, will be helpful for attracting further research interest over the semiconducting properties of tetra(aryl)porphyrin compounds for OFET applications.