Diketopyrrolopyrrole‐Based Conjugated Polymer Entailing Triethylene Glycols as Side Chains with High Thin‐Film Charge Mobility without Post‐Treatments

Abstract

Side chain engineering of conjugated donor–acceptor polymers is a new way to manipulate their optoelectronic properties. Two new diketopyrrolopyrrole (DPP)‐terthiophene‐based conjugated polymers PDPP3T‐1 and PDPP3T‐2, with both hydrophilic triethylene glycol (TEG) and hydrophobic alkyl chains, are reported. It is demonstrated that the incorporation of TEG chains has a significant effect on the interchain packing and thin‐film morphology with noticeable effect on charge transport. Polymer chains of PDPP3T‐1 in which TEG chains are uniformly distributed can self‐assemble spontaneously into a more ordered thin film. As a result, the thin film of PDPP3T‐1 exhibits high saturated hole mobility up to 2.6 cm2 V−1 s−1 without any post‐treatment. This is superior to those of PDPP3T with just alkyl chains and PDPP3T‐2. Moreover, the respective field effect transistors made of PDPP3T‐1 can be utilized for sensing ethanol vapor with high sensitivity (down to 100 ppb) and good selectivity.

Tunable Control of the Hydrophilicity and Wettability of Conjugated Polymers by a Postpolymerization Modification Approach

“…[7,16] In order to overcome these challenges, more recent work has shown that the incorporation of ionic or ethylene glycol based sidechains onto the backbone of the CP can promote ionic conductivity, [22,23] although the performance has been shown to be very sensitive to relative percentage of hydrophobic/hydrophilic groups on the backbone. [24] The addition of ethylene glycol chains to CPs has also been shown to promote closer π-stacking of conjugated backbones, [25,26] enhance the dielectric constant, [27,28] and afford higher charge carrier mobility in transistor devices [29,30] compared to the analogous alkylated polymers.…”

Challenge and Solution of Characterizing Glass Transition Temperature for Conjugated Polymers by Differential Scanning Calorimetry

“…Experimentally, precisely controlling the RDOC for CP is not straightforward. In general, the conventional DSC is not capable to quench the CPs to the supercooled, or completely amorphous state owing to the fast crystallization rate of CPs . For example, as shown in Figure S7, the crystallization of P3(2EB)T is inevitable upon cooling it from its melt state with conventional DSC even at 100 K min −1 , while faster cooling speed using flash DSC can trap P3(2EB)T into the fully amorphous phase using a cooling rate of 60,000 K min −1 (1,000 K s −1 ), as shown in Figure subsequently.…”

“…( T g discussed herein refers to backbone T g .) For example, it has been shown that for diketopyrrolopyrrole‐based (DPP) polymers, neither conventional DSC nor Flash DSC exhibits a clear T g …”

Electrode and dielectric layer interface device engineering study using furan flanked diketopyrrolopyrrole–dithienothiophene polymer based organic transistors

“…Accordingly, the interaction between dielectric and semiconductor layer is widely addressed through the appropriate choices of the SAM material, and its effective treatment on the dielectric surface before the semiconductor material is deposited on top of dielectric surface 20 . Among many possible silanes based SAM treatments on the SiO 2 surface, octyl trichlorosilane (OTS) is one of the most widely used 21 – 23 due to its appropriate alkyl chain length which enhances alkyl–alkyl interdigitation between the SAM alkyl chain and alkyl chain substituted on the conjugated backbone motifs.…”