Diketopyrrolopyrrole-based small molecules for solution-processed n-channel organic thin film transistors

Zhou, Qian; Jiang, Yu; Du, Tian; Wang, Zhongli; Liang, Ziqi; Han, Yang; Deng, Yunfeng; Tian, Hongkun; Geng, Yanhou

doi:10.1039/c9tc05038h

Cited by 22 publications

(13 citation statements)

References 58 publications

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“…[42][43][44][45] Dicyanomethylene-3-ethylrhodanine (RDN) and 3-(dicyanomethylidene)-indan-1-one (IC) are chosen as end functional groups because of their strong electron-withdrawing ability. [46][47][48][49] Particularly, thiophene-fused IC (ThIC) not only has a strong electron-withdrawing ability but could also provide better intermolecular interactions because of its potentially heteroatomic non-covalent interactions. [50][51][52] After Knoevenagel condensation reaction between TDPP-2CHO [53] and RDN, IC, or ThIC, respectively, three DPP-based small molecules were obtained with the high yield of 76% for TDPP-RDN, 79% for TDPP-IC, and 81% for TDPP-ThIC.…”

Section: Synthesis and Structure Characterizationmentioning

confidence: 99%

Unveiling the Interplay among End Group, Molecular Packing, Doping Level, and Charge Transport in N‐Doped Small‐Molecule Organic Semiconductors

Wang

et al. 2021

Adv Funct Materials

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Doped small molecules with high electrical conductivity are desired because they typically show a larger Seebeck coefficient and lower thermal conductivity than their polymer counterparts. However, compared with conjugated polymers, only a few small molecules can show high electrical conductivities. In this study, three n-type small-molecule organic semiconductors with different end functional groups are synthesized to explore the reasons for the low electrical conductivity issue in n-doped small-molecule semiconductors. Charge carrier mobility and doping level are usually considered as two major parameters for achieving high electrical conductivity. TDPP-ThIC with high electron mobility of 0.77 cm 2 V −1 s −1 and high electron affinity, which can be easily n-doped; however, it only displays an electrical conductivity ≈10 −3 S cm −1 . To explore the reasons, the single crystal structure of TDPP-ThIC and the grazing incidence wide-angle X-ray scattering of its n-doped films are carefully analyzed. TDPP-ThIC with a 1D column packing is disclosed and easily distorted by the enthetic n-dopants, which damages the charge transport pathways, and thereby results in low electrical conductivity. The results suggests that only high intrinsic charge carrier mobility and high doping level cannot guarantee high electrical conductivity, and keeping good charge transport pathways after doping is also critical.

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Section: Synthesis and Structure Characterizationmentioning

confidence: 99%

Unveiling the Interplay among End Group, Molecular Packing, Doping Level, and Charge Transport in N‐Doped Small‐Molecule Organic Semiconductors

Wang

et al. 2021

Adv Funct Materials

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“…With the additional aim of exploration on new n-type small organic semiconductors of which availability has been largely lagging p-type ones, − in this context, we synthesized a series of dicyanovinyl-end capped D–A-type DPP-based small molecules (C2C9CN, SiC4CN, and EH4PCN) composed of the same length of alkyl spacer but different end-functionalized side chains (alkyl- vs siloxane- vs phosphonate-end groups), as shown in Figure . We summarize the molecular structures and electrical properties of the state-of-the-art n-type DPP-based small molecules recently reported in the literature in Figure to access their status and trends in this field.…”

Section: Introductionmentioning

confidence: 99%

“…We summarize the molecular structures and electrical properties of the state-of-the-art n-type DPP-based small molecules recently reported in the literature in Figure to access their status and trends in this field. The successful examples include dicyanovinyl-terminated DPP (DPP-T-DCV), quinoidal-type DPP with the dicyanomethylene groups (TDPPQ-3), benzoidal-type DPPs with dicyanovinyl terminal groups and different spacers (TTDPPCN and BTDPPCN), DPP with 3-ethylrhodanine end group (DPP-T-RD), DPPs with halogenated 2-(3-oxo-indan-1-ylidene)-malononitrile terminal groups (DPP1012, DPP1012-4Cl, DPP1012-4F, and DPP68-4F), and DPPs containing siloxane side chains and dicyanovinyl (DPPT-Si-DCV), 3-ethylrhodanine (DPPT-Si-RD), or 2-(3-oxo-indan-1-ylidene)-malononitrile (DPPT-Si-INCN) terminal groups . The impacts of the end-functionalized side chains on the optical and electrochemical properties, thermal behaviors, film microstructure, and charge-transport characteristics are systematically investigated.…”

Section: Introductionmentioning

confidence: 99%

Effects of the Polarity and Bulkiness of End-Functionalized Side Chains on the Charge Transport of Dicyanovinyl-End-Capped Diketopyrrolopyrrole-Based n-Type Small Molecules

Kang

Lee

Kim

et al. 2021

ACS Appl. Mater. Interfaces

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When designing organic semiconductors, side-chain engineering is as important as modifying the conjugated backbone, which has a significant impact on molecular ordering, morphology, and thus electronic device performance. We have developed three dicyanovinyl-end-capped donor–acceptor diketopyrrolopyrrole-based n-type small molecules (C2C9CN, SiC4CN, and EH4PCN) bearing an identical length of alkyl spacer yet different end-functionalized side chains (i.e., alkyl-, siloxane-, and phosphonate-end pendants). The effects of the end-functionalized side chains on the intrinsic molecular properties, microstructure, and charge transport of the small-molecule series were investigated. In comparison with the alkyl-end side chains, incorporating siloxane-end side chains into the backbone facilitates 2D edge-on oriented high intergrain connectivity/crystallinity and compatibility with the substrate surface, whereas the phosphonate-end analogues have an adverse effect on the film-forming quality due to high polarity. Thereby, an organic field-effect transistor fabricated by SiC4CN shows the best electron mobility up to 1.59 × 10–1 cm2 V–1 s–1 along with a high current on/off ratio >105. This study contributes to our understanding of the role of the end-functionalized side chains (e.g., the effects of polarity and bulkiness of the end groups) for the development of high-performance semiconductors.

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“…In addition, in order to construct unipolar n-type semiconductor materials, electron-deficient groups are introduced into NDTI to reduce the LUMO energy level of the corresponding compound and promote effective electron injection. Among these, 3-(dicyanomethylidene)-indan-1-one (IC) as a strong electron-deficient group has been widely used in recent years. − Herein, we report two new NDTI-based small molecules ( NDTI-BTIC1 and NDTI-BTIC2 , Figure c) covalently connected by an electron-deficient NDTI-core and two 3-(dicyanomethylidene)-indan-1-one (IC) groups with alkoxy chain- or alkyl chain-substituted thiophene as bridging groups, respectively. Compared with the analogue NDTI-BTIC2 , NDTI-BTIC1 possesses a completely coplanar molecular structure, possibly attributed to noncovalent intramolecular S (thiophene)···O (alkoxy) interactions, which is proved by density functional theory (DFT) calculations.…”

Section: Introductionmentioning

confidence: 99%

End-Capping π-Conjugated Naphthodithiophene Diimide (NDTI)-Based Triads with Noncovalent Intramolecular S···O Interactions: A Route towards High-Performance Solution-Processable Air-Stable n-Type Semiconductors

Ran

Zheng

et al. 2021

ACS Appl. Electron. Mater.

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Introducing noncovalent intramolecular interactions into functional π-conjugated organic molecules or polymers is a useful method to improve the performance of organic semiconducting devices. In this study, two small molecules based on naphthodithiophene diimide (NDTI), NDTI-BTIC1 and NDTI-BTIC2, were successfully designed and synthesized by covalently connecting an electron-deficient NDTI-core and two 3-(dicyanomethylidene)-indan-1-one (IC) groups with thiophene substituted by an alkoxy chain or alkyl chain, respectively. Density functional theory (DFT) calculations on the optimized geometries of the triads predict that the existence of noncovalent intramolecular S (thiophene)···O (alkoxy) interactions is possible in NDTI-BTIC1. The molecular orbital distributions of NDTI-BTIC1 and NDTI-BTIC2 show that the lowest unoccupied molecular orbitals (LUMOs) are delocalized in the whole molecule, implying the possibility to show n-type transport characteristics. The two molecules further demonstrated LUMOs at a low altitude of −4.37 to −4.45 eV, low enough for the stable transmission of electrons in the atmosphere. The solution-processing method was used to prepare transistors based on the two molecules’ bottom-gate top-contact (BGTC), which exhibited unipolar n-type field-effect transistor (FET) characteristics in the air. The FET performance of NDTI-BTIC1 is higher than that of NDTI-BTIC2 in both the as-spun and thermal annealed films, possibly attributed to the existence of noncovalent intramolecular S···O interactions in NDTI-BTIC1. Moreover, the maximum electron mobility of NDTI-BTIC1 obtained at 150 °C thermal annealing is improved by one order of magnitude compared to that of NDTI-BTIC2, being 0.17 and 0.085 cm2 V–1 s–1, respectively. The transport difference of the two molecules was proved by film morphology analysis. The results show that constructing noncovalent intramolecular S···O conformational locks between the TIC unit and NDTI can improve the organic field-effect transistor (OFET) devices’ performance through reasonable molecular design strategies.

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Diketopyrrolopyrrole-based small molecules for solution-processed n-channel organic thin film transistors

Abstract: n-Type small molecules exhibit a highly reliable mobility of up to 1.05 cm2 V−1 s−1 in solution-processed organic thin film transistors.

Cited by 22 publications

References 58 publications

Unveiling the Interplay among End Group, Molecular Packing, Doping Level, and Charge Transport in N‐Doped Small‐Molecule Organic Semiconductors

Unveiling the Interplay among End Group, Molecular Packing, Doping Level, and Charge Transport in N‐Doped Small‐Molecule Organic Semiconductors

Effects of the Polarity and Bulkiness of End-Functionalized Side Chains on the Charge Transport of Dicyanovinyl-End-Capped Diketopyrrolopyrrole-Based n-Type Small Molecules

End-Capping π-Conjugated Naphthodithiophene Diimide (NDTI)-Based Triads with Noncovalent Intramolecular S···O Interactions: A Route towards High-Performance Solution-Processable Air-Stable n-Type Semiconductors

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