Work function difference of naphthyl end-capped oligothiophene in different crystal alignments studied by Kelvin probe force microscopy

The performance of organic semiconductor devices is strongly affected by the interface energetics at junctions between constituent materials. A large group semiconductors consists rodlike small molecules that crystallize upon deposition with a molecular orientation dependent on specifics molecule–molecule and molecule–substrate interactions. By means Kelvin probe force microscopy (KPFM), this work studies naphthyl end-capped oligothiophene, 5,50-bis(naphth-2-yl)-2,20-bithiophene (NaT2), deposited samples pristine SiO 2 graphene-covered . crystal NaT2 substrate which it deposited. On , are predominately upright standing, forming crystallites distinct terrace heights 0 ± 1 nm Measurements indicate formation an initial wetting layer in NaT2- system for standing molecules. When graphene, additionally form fibrous structures 10 ? 115 consisting lying down (face-on orientation). Using KPFM, difference local contact potential (CPD) face-on oriented graphene measured to be 16 04 V indicating function two configurations, confirmed through Density Functional Theory calculations. • molecule its substrate. KPFM measures related function. can distinguish different orientations graphene- DFT reveals electron distribution causes