Conjugated Random Donor–Acceptor Copolymers of [1]Benzothieno[3,2‑<i>b</i>]benzothiophene and Diketopyrrolopyrrole Units for High Performance Polymeric Semiconductor Applications

Three-component random copolymers having different ratios of [1]­benzothieno­[3,2-<i>b</i>]­benzothiophene (BTBT) and diketopyrrolopyrrole (DPP) units were synthesized, and their application in organic field effect transistors (OFET) has been discussed. These low band gap polymers exhibit p-type semiconducting properties, and it has been observed that increase in the percentage composition of the fused chalcogenophene (BTBT) in the polymer backbone significantly improves the charge carrier mobility (μ_h) up to 2.47 cm² V^–1 s^–1. The GIXRD technique and AFM have been used to explain the influence of BTBT on the nature of molecular packing in the polymer thin films. These results unveil the role of the effective conjugation length as well as the intermolecular ordering of the polymer chains on the charge carrier transport in OFET

Tuning the Semiconducting Behaviors of New Alternating Dithienyldiketopyrrolopyrrole–Azulene Conjugated Polymers by Varying the Linking Positions of Azulene

Three new conjugated polymers <b>DPPA1</b>, <b>DPPA2</b>, and <b>DPPA3</b> with dithienyldiketopyrrolopyrrole (DPP) and azulene moieties were synthesized and characterized. The five-membered rings of azulene are connected with DPP in <b>DPPA1</b> and <b>DPPA2</b>, whereas the seven-membered ring of azulene is incorporated into the backbone of <b>DPPA3</b>. The LUMO energy of <b>DPPA3</b>, which was determined on the basis of the respective cyclic voltammograms and absorption spectra, is lower than those of <b>DPPA1</b> and <b>DPPA2</b>. OFETs were successfully fabricated with thin films of <b>DPPA1</b>, <b>DPPA2</b>, and <b>DPPA3</b>. Thin films of <b>DPPA1</b> and <b>DPPA2</b> exhibit p-type semiconducting properties with hole mobilities up to 0.97 cm² V^–1 s^–1, whereas typical ambipolar behavior is found for thin film of <b>DPPA3</b> with hole and electron mobilities reaching 0.062 cm² V^–1 s^–1 and 0.021 cm² V^–1 s^–1, respectively. The results reveal that semiconducting properties of <b>DPPA1</b>, <b>DPPA2</b>, and <b>DPPA3</b> can be tuned by varying the linkage positions of azulene with DPP moieties. Furthermore, <b>DPPA1</b>, <b>DPPA2</b>, and <b>DPPA3</b> were tested preliminarily as photovoltaic materials. The power conversion efficiency (PCE) reaches 2.04% for the blending thin film <b>DPPA1</b> with PC₇₁BM

New Donor–Acceptor–Donor Molecules with Pechmann Dye as the Core Moiety for Solution-Processed Good-Performance Organic Field-Effect Transistors

In this paper, we report the synthesis and characterization of two new D-A-D molecules (<i>E</i>)-5,5′-bis­(5-(benzo­[<i>b</i>]­thiophen-2-yl)­thiophen-2-yl)-1,1′-bis­(2-ethyl- hexyl)-[3,3′-bipyrrolylidene]-2,2′(1<i>H</i>,1′<i>H</i>)-dione (<b>BTBPD</b>) and (<i>E</i>)-5,5′-bis- (5-(benzo­[<i>b</i>]­furan-2-yl)­thiophen-2-yl)-1,1′-bis­(2-ethylhexyl)-[3,3′-bipyrrolylidene]-2,2′(1<i>H</i>,1′<i>H</i>)-dione (<b>BFBPD</b>). They entail bipyrrolylidene-2,2′(1<i>H</i>,1′<i>H</i>)-dione (<b>BPD</b>, known as Pechmann dye) as the electron-accepting core that is flanked by two benzo­[<i>b</i>]­thiophene moieties and two benzo­[<i>b</i>]­furan moieties, respectively. Crystal structures of <b>BTBPD</b> and <b>BFBPD</b> provide solid evidence for the intermolecular donor–acceptor (D-A) interactions, which are favorable for improving charge transport performance. Organic field-effect transistors (OFETs) were prepared based on thin films of <b>BTBPD</b> and <b>BFBPD</b> through solution-processed technique. OFETs of <b>BTBPD</b> exhibit relatively high hole mobility up to 1.4 cm² V^–1 s^–1 with high on/off ratio up to 10⁶. In comparison, the hole mobility of OFETs with <b>BFBPD</b> (0.14 cm² V^–1 s^–1) is relatively low, because of the poor thin-film morphology and low molecular ordering, even after annealing. Thin-film morphological and XRD studies were carried out to understand the variation of hole mobilities after annealing at different temperatures. The present studies clearly demonstrate the potentials of <b>BPD</b> that is planar and polar as the electron-acceptor moiety to build D-A molecules for organic semiconductors with good performance

New Donor–Acceptor–Donor Molecules with Pechmann Dye as the Core Moiety for Solution-Processed Good-Performance Organic Field-Effect Transistors

In this paper, we report the synthesis and characterization of two new D-A-D molecules (<i>E</i>)-5,5′-bis­(5-(benzo­[<i>b</i>]­thiophen-2-yl)­thiophen-2-yl)-1,1′-bis­(2-ethyl- hexyl)-[3,3′-bipyrrolylidene]-2,2′(1<i>H</i>,1′<i>H</i>)-dione (<b>BTBPD</b>) and (<i>E</i>)-5,5′-bis- (5-(benzo­[<i>b</i>]­furan-2-yl)­thiophen-2-yl)-1,1′-bis­(2-ethylhexyl)-[3,3′-bipyrrolylidene]-2,2′(1<i>H</i>,1′<i>H</i>)-dione (<b>BFBPD</b>). They entail bipyrrolylidene-2,2′(1<i>H</i>,1′<i>H</i>)-dione (<b>BPD</b>, known as Pechmann dye) as the electron-accepting core that is flanked by two benzo­[<i>b</i>]­thiophene moieties and two benzo­[<i>b</i>]­furan moieties, respectively. Crystal structures of <b>BTBPD</b> and <b>BFBPD</b> provide solid evidence for the intermolecular donor–acceptor (D-A) interactions, which are favorable for improving charge transport performance. Organic field-effect transistors (OFETs) were prepared based on thin films of <b>BTBPD</b> and <b>BFBPD</b> through solution-processed technique. OFETs of <b>BTBPD</b> exhibit relatively high hole mobility up to 1.4 cm² V^–1 s^–1 with high on/off ratio up to 10⁶. In comparison, the hole mobility of OFETs with <b>BFBPD</b> (0.14 cm² V^–1 s^–1) is relatively low, because of the poor thin-film morphology and low molecular ordering, even after annealing. Thin-film morphological and XRD studies were carried out to understand the variation of hole mobilities after annealing at different temperatures. The present studies clearly demonstrate the potentials of <b>BPD</b> that is planar and polar as the electron-acceptor moiety to build D-A molecules for organic semiconductors with good performance