Cyanostyrylthiophene-Based Ambipolar Conjugated Polymers: Synthesis, Properties, and Analyses of Backbone Fluorination Effect

Abstract

Herein, we report the synthesis and characterization of a series of ambipolar cyanostyryl­thiophene (CST)-based conjugated polymers without or with fluorine substituents, namely PD-CST, PD-3F-CST, PD-23F-CST, and PD-25F-CST. With the change of the number or incorporating position of fluorine substitutes on the novel CST unit, the electron mobilities of field-effect transistors based on these polymers dramatically increased from 0.0015 cm2 V–1 s–1 for PD-CST, 0.13 cm2 V–1 s–1 for PD-3F-CST, and 0.25 cm2 V–1 s–1 for PD-23F-CST to 0.53 cm2 V–1 s–1 for PD-25F-CST. AFM and GIXRD investigation indicated that the annealed PD-25F-CST thin film possesses stronger crystallization tendency and highly ordered lamellar packing than those of the other polymers. Further theoretical calculations and single-crystal X-ray diffraction analysis deeply revealed the remarkable influences of the number and incorporating position of fluorine substitutes on the frontier orbital energy levels, backbone conformation, and charge transport properties of polymer semiconductors.

A Solution Processable Dithioalkyl Dithienothiophene (DSDTT) Based Small Molecule and Its Blends for High Performance Organic Field Effect Transistors

“…The LUMO of DSDTT and 1 are −1.95 and −2.50 eV, respectively. Finally, density functional theory calculations at the B3LYP/6-31G (d) level (Figure S4) support energy trends and large delocalization of the frontier molecular orbitals over the whole molecules, which favor efficient charge transport. − …”

Synthesis and Performance of (E)-3-Phenyl-2-(thiophen-2-yl)acrylonitrile-Based Small-Molecule Semiconductors

“…25 The DPP-3FBVCNT-based devices showed almost similar threshold voltages to those of DPP-2FBVCNT-based devices, maybe because of their nearly similar HOMO/LUMO energy levels, which might be due to the similar conformational lock effects from the F…H bonds in the two compounds according to previous research performed by our group. 26,27 From the above results, it can be seen that in these DPP-DBVCNT-based organic conjugated small molecules, the substitution and the position of the F atoms introduced into the benzene rings of the donor units had significant effects on the charge carrier transport. It is interesting to note that the introduction of one F atom into each of the donor benzene rings on both sides of the DPP acceptor unit was beneficial to make the performance of the DPP-BVCNT-based compound be changed from p-type to ambipolar.…”

Tunable charge-transport polarity in thienothiophene–bisoxoindolinylidene-benzodifurandione copolymers for high-performance field-effect transistors

“…Despite the well-established side-chain engineering concept, 9,11,12 backbone modification by halogen and chalcogen atoms also plays vital roles in controlling the opto-electronics properties. [13][14][15] The underlying origin includes electronic and steric effects, both of which are crucial to the charge transport processes from a mechanistic perspective. The electronic effects modulate the conjugation that provides precise control over carrier injection from electrodes to the semiconductor layer, whereas the steric effects influence the self-aggregation behavior that stems from the conformations and noncovalent interactions.…”