New Semiconductors Based on 2,2′-Ethyne-1,2-diylbis[3-(alk-1-yn-1-yl)thiophene] for Organic Opto-Electronics

Abstract

We report the synthesis and properties of three novel acetylenic materials based on the new electron-rich building block, 2,2′-ethyne-1,2-diylbis[3-(alk-1-yn-1-yl)thiophene] (EBT). The synthesis of this new nonacene core is efficient and straightforward, and variation among n-hexyl, n-tetradecyl, and 2ethylhexyl substituents substantially impacts the materials properties. Appending 2-ethylhexyl substituted diketopyrrolopyrrole (DPP) units to either terminus of the EBT core yields a series of low band gap molecules that are characterized in detail by a range of experimental microstructure and electronic structure probes and by density functional theory (DFT) computation. Detailed morphology/microstructure characterization of spin-cast films by X-ray diffraction and AFM reveals instructive microstructure and electronic/photovoltaic response relationships in both organic field-effect transistors and bulk-heterojunction organic photovoltaic cells. Thus, the former devices exhibit hole mobilities (μ h ) as large as ∼0.2 cm 2 /(V s) which fall as thermal annealing increases long-range order. The latter devices using PC 61 BM as the electron acceptor exhibit power conversion efficiencies as high as ∼2%, which appear to fall as the materials become less ordered. These results are in accord with a model where evolving grain boundaries and crystallinity impedes hole transport and excitonic charge generation.

Thieno[3,2‐b]thiophene‐Diketopyrrolopyrrole‐Based Quinoidal Small Molecules: Synthesis, Characterization, Redox Behavior, and n‐Channel Organic Field‐Effect Transistors

“…In the past two decades, the performances of OFETs have been significantly enhanced as a result of intense research efforts towards the development of new π‐conjugated semiconducting materials 8–15. Among the most successful molecular building blocks, diketopyrrolopyrrole (DPP) has attracted considerable attention for the construction of a large number of organic semiconductors because of its electron‐deficient nature, planar skeleton, and ability to form hydrogen bonds 16–19. There also exist numerous reports on DPP‐based high‐performance polymers 20–25.…”

“…[8][9][10][11][12][13][14][15] Among the most successful molecular building blocks, diketopyrrolopyrrole (DPP) has attracted considerable attention for the construction of a large number of organic semiconductors because of its electron-deficient nature, planar skeleton, and ability to form hydrogen bonds. [16][17][18][19] There also exist numerous reports on DPP-based high-performance polymers. [20][21][22][23][24][25] In comparison, DPP-based small molecules offering advantages over polymers in terms of purification and reproducibility have been studied to a far lesser extent.…”

Direct C–H arylation for various Ar-cored diketopyrrolopyrrole containing small molecules in solution-processed field-effect transistors

“…8 Specically, DPP containing conjugated polymers exhibited excellent OFET performance with a hole mobility above 13 cm 2 V À1 s À1 and an electron mobility of 7 cm 2 V À1 s À1 . [21][22][23] In previous studies, most of DPP derivatives were commonly synthesized by Stille, Suzuki or Negishi cross-coupling reactions, where one arene is substituted with a functional group (Br, I, OTf, etc. [14][15][16] Furthermore, the specic structure and conrmed molecular weight of small molecules enables better understanding of structure-property relationships and thus provides guidance to the design of highperformance semiconducting materials.…”

Extended Conjugated Donor–Acceptor Molecules with E‐(1,2‐Difluorovinyl) and Diketopyrrolopyrrole (DPP) Moieties toward High‐Performance Ambipolar Organic Semiconductors

“…[5a, 8, 15] Most of these DPPbased D-A molecules, especially small molecules, exhibit ptype semiconducting behavior. [16] Only a few DPP-based small molecules that can be solution-processed exhibit m h values above 0.1 cm 2 V À1 s À1 . [16] Ambipolar and n-type semiconductors are seldom reported for DPP-based small molecules.…”

“…[16] Only a few DPP-based small molecules that can be solution-processed exhibit m h values above 0.1 cm 2 V À1 s À1 . [16] Ambipolar and n-type semiconductors are seldom reported for DPP-based small molecules. [17] Scheme 1 shows the representative DPP-based D-A molecules and their HOMO/LUMO energy levels.…”