Charge transport properties of 5,6,7-trithiapentacene-13-one (TTPO) and its fluorinated derivatives

Abstract

Three fluorinated 5,6,7-trithiapentacene-13-one (TTPO) derivatives were designed by replacing some hydrogen atoms of TTPO with fluorine atoms. Based on the X-ray structure of TTPO, the crystal structures of the fluorinated TTPO were optimized by the dispersion-corrected density functional theory (DFT-D). The charge transport properties of TTPO and its derivatives as potential n-channel organic semiconductors (OSCs) have been investigated at molecular and crystal level by means of density functional theory (DFT) calculations coupled with the incoherent charge hopping model. TTPO molecule has a low-lying LUMO level while its fluorinated derivatives have a further low LUMO level that enable their stability when exposed to air. Electron affinities (EA) also show this increasing stability after fluorination. The reorganization energies for both electron and hole transports increase after fluorination. The electron transport mobility at room temperature for TTPO and its fluorinated derivatives are in the range from 0.09 to 1.01cm2V−1s−1. This indicates the four compounds are candidates as stable n-channel OSC materials under favorable device conditions. In addition, the angular-dependent analysis for electron mobility shows that the electron transport is remarkably anisotropic and the maximum μe appears along face-to-face stacking direction with the largest electronic couplings.