Fine Molecular Tuning of Diketopyrrolopyrrole-Based Polymer Semiconductors for Efficient Charge Transport: Effects of Intramolecular Conjugation Structure

Abstract

To improve the charge carrier mobility of diketopyrrolopyrrole donor−acceptor copolymer semiconductors, the length of the donor building block is controlled using vinylene moieties, and its effects on crystalline structure and charge transport are systematically studied. We synthesize P29-DPP-TBT with two vinylene linkages between thiophene units and compare it with P29-DPP-TVT with single vinylene linkage. Density functional theory calculations predict enhanced backbone planarity of P29-DPP-TBT compared to P29-DPP-TVT, which can be related to the increased conjugation length of P29-DPP-TBT as proved by the increased free exciton bandwidth extracted from UV−vis absorption spectra and the wavenumber shift of the C−C peaks to higher values in Raman spectra. From two-dimensional grazing incident X-ray diffraction studies, it is turned out that the paracrystalline disorder is lower in P29-DPP-TBT than in P29-DPP-TVT. Near-edge X-ray absorption fine structure spectroscopy reveal that more edge-on structure of polymer backbone is formed in the case of P29-DPP-TBT. By measuring the temperature dependence of the charge carrier mobilities, it is turned out that the activation energy for charge hopping is lower for P29-DPP-TBT than for P29-DPP-TVT. Collectively, these results imply that the substitution of extended π-conjugated donor moiety of polymeric semiconductors can yield a more planar backbone structure and thus enhanced intermolecular interaction which enables more perfect crystalline structure as well as enhanced charge transport behavior.

Synergistically Improved Molecular Doping and Carrier Mobility by Copolymerization of Donor–Acceptor and Donor–Donor Building Blocks for Thermoelectric Application

“…Due to better miscibility between dopants and g 3 2T‐TT, charge transfer probably preferentially occurs at the region with much g 3 2T‐TT. To support this hypothesis, Raman spectroscopy was employed to analyze the change of the vibrational modes of PDPP‐TT, PDPP‐g 3 2T 0.3 and Pg 3 2T‐TT upon doping [ 46–48 ] (details are described in Table S4, Supporting Information). Figure a show the Raman signals of these films with normalized intensity of the band peaked at a specific mode.…”

“…Mode c and mode d (marked with asterisks) are used as relative modes, corresponding to CC/CC stretching/shrinking on thiophene and CC stretching in the DPP unit, respectively, to monitor the DPP2T unit. [ 48 ] It is found that the relative intensities of these two modes are unchanged upon doping for PDPP‐TT, whereas the intensity mainly assigned to CC stretching in the thienothiophene core (mode a and mode b) increases. This suggests that the doping reaction mostly occurs on thienothiophene unit and the electron‐withdrawing DPP unit is inactive for dopants.…”

A Quinacridone-Diphenylquinoxaline-Based Copolymer for Organic Field-Effect Transistors

“…Research into organic field-effect transistors (OFETs) has been committed to the advancement of organic semiconducting materials and device engineering technologies in the last decades [1,2,3,4,5]. Current investigations of OFETs are aiming to rapidly meet the rising demand for large-area or flexible sensors and displays, and driving elements for RF identification tags, as well as many other lower-cost functional devices [6,7].…”

Electrohydrodynamic-Jet (EHD)-Printed Diketopyrrolopyroole-Based Copolymer for OFETs and Circuit Applications

“…In this study, we demonstrated EHD printing of a diketopyrrolopyrrole (DPP)-based copolymer, namely poly[2,5-bis(7-decylnonadecyl)pyrrolo[3,4-c]pyrrole-1,4(2 H ,5 H )-dione-(E)-(1,2-bis(5-(thiophen-2-yl)selenophen-2-yl)ethene) (P-29-DPPDTSE), as shown in Figure 1a, to fabricate patterned OFETs. DPP-based copolymers constitute a kind of donor-acceptor (D-A) conjugated copolymer and have been studied intensively due to their planar backbones and strong inter/intramolecular charge transport [15,16]. Various DPP-based copolymers have been investigated for use in OFETs [5,16,17,18,19,20,21].…”

“…DPP-based copolymers constitute a kind of donor-acceptor (D-A) conjugated copolymer and have been studied intensively due to their planar backbones and strong inter/intramolecular charge transport [15,16]. Various DPP-based copolymers have been investigated for use in OFETs [5,16,17,18,19,20,21]. Of these copolymers, for this study, we chose P-29-DPPDTSE in a previously reported investigation due to its high field-effect mobility ( μ FET ) [5].…”