Indacenodithiazole-Ladder-Type Bridged Di(thiophene)-Difluoro-Benzothiadiazole-Conjugated Copolymers as Ambipolar Organic Field-Effect Transistors

Abstract

A series of four donor–acceptor conjugated copolymers P1–P4 with linear and branched side chains based on a ladder-type indacenodithiazole (IDTz) moiety containing an electron-deficient thiazole unit are copolymerized with di-2-thienyl-2,1,3-benzothiadiazole (DTBT) and 4,7-di­(thien-2-yl)-5,6-difluoro-2,1,3-benzothiadiazole (DTBTff) as building blocks. Their optical, electrochemical, and thermal properties and charge transport behavior in organic field-effect transistors (OFETs) are studied. All copolymers exhibit nearly identical features in solution with good solubility. In the solid state, P1 does not exhibit a significant shift, while P3 shows a 27 nm red shift, thus illustrating the influence of the side chain. In the case of copolymers P1 and P2 having linear side chains, there is a clear effect of fluorination on the film morphology, while it is less pronounced in the case of polymers P3 and P4 having branched side chains. All copolymers P1–P4 have similar highest occupied molecular orbitals regardless of fluorination, while fluorinated polymers P2 and P4 result in an increase in the lowest unoccupied molecular orbital. In addition, density functional theory calculations reveal that the energy levels of IDTz are down-shifted in comparison to its IDT counterpart containing an electron-rich thiophene unit. OFETs based on all copolymers exhibit ambipolar behavior; among the four copolymers, P2 having a linear dodecyl side chain exhibits remarkable transport properties with saturated hole mobility as high as 0.87 cm2 V–1 s–1, while P3 exhibits the highest electron mobility of up to 0.50 cm2 V–1 s–1. Our results set an interesting path to further utilize the electron-deficient thiazole block in semiconducting materials.

Conjugated polymers for functional applications: lifetime and performance of polymeric organic semiconductors in organic field‐effect transistors

“…A variety of IDT copolymers (Fig. 4, Pp9–12) showed appreciable hole and electron mobilities, 0.87 and 0.50 cm 2 V −1 s −1 , respectively, and high thermal stability with only 5% weight loss at 365 °C 53 . However, these measurements were not performed in tandem.…”

Microwave-Assisted Palladium-Catalyzed Cross-Coupling Reactions: Generation of Carbon–Carbon Bond

“…Although the reaction is very stable to oxygen and moisture and tolerates numerous functional groups, it raises the environmental issue seriously for the employment of the toxic organostannanes [89]. Under microwave irradiation, nevertheless, the reaction has been widely employed in polymerizations [90] and few protocols have been developed and published during the last two decades. Microwave-accelerated one-pot hydrostannylation/Stille coupling reaction was reported for the conversion of 1-alkynes to 1,3-dienes or styrenes.…”

Modern Development in Copper‐ and Nickel‐Catalyzed Cross‐Coupling Reactions: Formation of Carbon‐Carbon and Carbon‐Heteroatom bonds under Microwave Irradiation Conditions

“…Microwave‐assisted chemistry started to empower researchers toward important innovations in advanced nanomaterial design and development. It quantitatively and selectively allows facile emergence of valuable organic compounds, polymers and nanomaterials in extremely short reaction time than by applying conventional heating [22–24] . Additionally, the use of microwave irradiation heating offers significant energy‐saving processes with low level of formation of side reactions; therefore, it accomplishes the conditions of green chemistry.…”

“…It quantitatively and selectively allows facile emergence of valuable organic compounds, polymers and nanomaterials in extremely short reaction time than by applying conventional heating. [22][23][24] Additionally, the use of microwave irradiation heating offers significant energy-saving processes with low level of formation of side reactions; therefore, it accomplishes the conditions of green chemistry. Microwave heating could be designateed as a Bunsen burner of the current century, as it is predominantly used.…”