%0 Journal Article %A Salammal, Shabi Thankaraj %A Zhang, Zhongqiang %A Chen, Jiehuan %A Chattopadhyay, Basab %A Wu, Jiake %A Fu, Lei %A Fan, Congcheng %A Chen, Hongzheng %D 2016 %T Polymorphic Phase-Dependent Optical and Electrical Properties of a Diketopyrrolopyrrole-Based Small Molecule %U https://acs.figshare.com/articles/journal_contribution/Polymorphic_Phase-Dependent_Optical_and_Electrical_Properties_of_a_Diketopyrrolopyrrole-Based_Small_Molecule/3507224 %R 10.1021/acsami.6b05084.s001 %2 https://acs.figshare.com/ndownloader/files/5572394 %K twist conformation %K band gap decreases %K phase transition %K phases show ambipolar charge transport %K hole mobility %K Electrical Properties %K DPP %K polymorphic conformations %K 1.5 eV %K annealing treatments %X Four different polymorphic conformations of diethyl 5,5′-[5,5′-[2,5-bis­(2-ethylhexyl)-3,6-dioxo-2,3,5,6-tetrahydropyrrolo­[3,4-c]­pyrrole-1,4-diyl]­bis­(thiophene-5,2-diyl)]­difuran-2-carboxylate (DPP-(CF)2), namely, DPP-(CF)2-α, DPP-(CF)2-β, DPP-(CF)2-γ, and DPP-(CF)2-ω, were identified from X-ray diffraction analysis conducted on their thin films and single crystals. Highly crystalline and well-textured thin films of these four polymorphs were successfully prepared via postgrowth solvent vapor and thermal annealing treatments to investigate the polymorphic phase-dependent optical and electrical properties of DPP-(CF)2. Interestingly, during the phase transition from DPP-(CF)2-α to DPP-(CF)2-ω, the optical band gap decreases from 1.75 to 1.5 eV because of the enhanced π–π interaction between the neighboring molecules. Except for DPP-(CF)2-γ, the other three phases show ambipolar charge transport. Although DPP-(CF)2-β and DPP-(CF)2-γ exhibit a similar way of packing, a small increment in the π–π-stacking distance (0.006 Å) and twist conformation of the grafted electron-donating moieties of DPP-(CF)2-γ are found to reduce its hole mobility. %I ACS Publications