Embedding electron-deficient nitrogen atoms in polymer backbone towards high performance n-type polymer field-effect transistors

Dai, Ya‐Zhong; Ai, Na; Lü, Yang; Zheng, Yu-Qing; Dou, Jin-Hu; Shi, Ke; Lei, Ting; Wang, Jieyu; Pei, Jian

doi:10.1039/c6sc01380e

Cited by 88 publications

(80 citation statements)

References 41 publications

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“…The dihedral angle between the NDI block and bithiophene blocks is 40° in PNDI2TEG‐2T, while The PNDI2TEG‐2Tz exhibits a dihedral angle of only 1°. These results indicate an improved molecular planarity after introducing sp 2 ‐N atoms, which is consistent with previous reports …”

Section: Thermoelectric Properties Of Solution‐processed N‐type Conjusupporting

confidence: 93%

N‐Type Organic Thermoelectrics of Donor–Acceptor Copolymers: Improved Power Factor by Molecular Tailoring of the Density of States

et al. 2018

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It is demonstrated that the n-type thermoelectric performance of donor-acceptor (D-A) copolymers can be enhanced by a factor of >1000 by tailoring the density of states (DOS). The DOS distribution is tailored by embedding sp -nitrogen atoms into the donor moiety of the D-A backbone. Consequently, an electrical conductivity of 1.8 S cm and a power factor of 4.5 µW m K are achieved. Interestingly, an unusual sign switching (from negative to positive) of the Seebeck coefficient of the unmodified D-A copolymer at moderately high dopant loading is observed. A direct measurement of the DOS shows that the DOS distributions become less broad upon modifying the backbone in both pristine and doped states. Additionally, doping-induced charge transfer complexes (CTC) states, which are energetically located below the neutral band, are observed in DOS of the doped unmodified D-A copolymer. It is proposed that charge transport through these CTC states is responsible for the positive Seebeck coefficients in this n-doped system. This is supported by numerical simulation and temperature dependence of Seebeck coefficient. The work provides a unique insight into the fundamental understanding of molecular doping and sheds light on designing efficient n-type OTE materials from a perspective of tailoring the DOS.

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Section: Thermoelectric Properties Of Solution‐processed N‐type Conjusupporting

confidence: 93%

N‐Type Organic Thermoelectrics of Donor–Acceptor Copolymers: Improved Power Factor by Molecular Tailoring of the Density of States

et al. 2018

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“…This resulted in P39 having an n‐type mobility of 1.7 cm 2 V −1 s −1 , when using a similar device architecture to Dou et al Replacing the vinylene comonomer with bithiophene ( P40 ) allowed Lei et al to fabricate top‐gate bottom‐contact devices with electron mobilities up to 1.74 cm 2 V −1 s −1 ; impressively, devices that were both fabricated and tested under ambient conditions maintained an electron mobility of up to 1.45 cm 2 V −1 s −1 * . Dai et al reported an identical polymer to P40 , but this time a pyridyl nitrogen was incorporated into the peripherally fused phenyl rings to produce azaBDO ( P41 ) . The nitrogen atom acted to further lower the LUMO, while encouraging a greater degree of backbone planarity.…”

Section: N‐type Organic Semiconductorssupporting

confidence: 62%

Recent Progress in High‐Mobility Organic Transistors: A Reality Check

et al. 2018

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Over the past three decades, significant research efforts have focused on improving the charge carrier mobility of organic thin-film transistors (OTFTs). In recent years, a commonly observed nonlinearity in OTFT current-voltage characteristics, known as the "kink" or "double slope," has led to widespread mobility overestimations, contaminating the relevant literature. Here, published data from the past 30 years is reviewed to uncover the extent of the field-effect mobility hype and identify the progress that has actually been achieved in the field of OTFTs. Present carrier-mobility-related challenges are identified, finding that reliable hole and electron mobility values of 20 and 10 cm V s , respectively, have yet to be achieved. Based on the analysis, the literature is then reviewed to summarize the concepts behind the success of high-performance p-type polymers, along with the latest understanding of the design criteria that will enable further mobility enhancement in n-type polymers and small molecules, and the reasons why high carrier mobility values have been consistently produced from small molecule/polymer blend semiconductors. Overall, this review brings together important information that aids reliable OTFT data analysis, while providing guidelines for the development of next-generation organic semiconductors.

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“…In order to enhance the electron‐deficient property of the BDOPV unit, Dai et al replaced the benzene ring of the BDOPV unit with a pyridine ring (AzaBDOPV) and copolymerized the modified acceptor unit with bithiophene ( P51 ) . Since the pyridine unit exhibited a strong electron‐withdrawing character, P51 had a LUMO level of −4.3 eV, suitable for efficient electron injection, whereas the P51 ‐based OFET exhibited a μ e value of 3.22 cm 2 V −1 s −1 .…”

Section: Molecular Design Strategies For High‐performance D–a‐conjugamentioning

confidence: 99%

“…In a manner similar to the approach applied to the polymer P51 , Yue et al synthesized an IIG derivative containing sp 2 ‐nitrogen atoms (AzaIIG) and reported copolymer of the AzaIIG unit and the BT unit ( P54 ) at a μ e value of 1.00 cm 2 V −1 s −1 . The resulting polymer, P54 , exhibited a low LUMO energy level of about −4.0 eV owing to the strong electron‐deficient of the AzaIIG unit.…”

Section: Molecular Design Strategies For High‐performance D–a‐conjugamentioning

confidence: 99%

Donor–Acceptor‐Conjugated Polymer for High‐Performance Organic Field‐Effect Transistors: A Progress Report

Kim

Ryu

Park

et al. 2019

Adv Funct Materials

331

318

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Polymeric semiconductors have demonstrated great potential in the mass production of low-cost, lightweight, flexible, and stretchable electronic devices, making them very attractive for commercial applications. Over the past three decades, remarkable progress has been made in donor-acceptor (D-A) polymer-based field-effect transistors, with their charge-carrier mobility exceeding 10 cm 2 V −1 s −1 . Numerous molecular designs of D-A polymers have emerged and evolved along with progress in understanding the charge transport physics behind their high mobility. In this review, the current understanding of charge transport in polymeric semiconductors is covered along with significant features observed in high-mobility D-A polymers, with a particular focus on polymeric microstructures. Subsequently, emerging molecular designs with further prospective improvements in charge-carrier mobility are described. Moreover, the current issues and outlook for future generations of polymeric semiconductors are discussed.

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Embedding electron-deficient nitrogen atoms in polymer backbone towards high performance n-type polymer field-effect transistors

Abstract: The low LUMO level and the conformation-locked planar backbone provide polymer AzaBDOPV-2T with electron mobilities over 3.22 cm2 V–1 s–1 tested in air.

Cited by 88 publications

References 41 publications

N‐Type Organic Thermoelectrics of Donor–Acceptor Copolymers: Improved Power Factor by Molecular Tailoring of the Density of States

N‐Type Organic Thermoelectrics of Donor–Acceptor Copolymers: Improved Power Factor by Molecular Tailoring of the Density of States

Recent Progress in High‐Mobility Organic Transistors: A Reality Check

Donor–Acceptor‐Conjugated Polymer for High‐Performance Organic Field‐Effect Transistors: A Progress Report

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