This review highlights recent major progress in the development of organic semiconductors as electron transport n-channel materials in organic field effect transistors (OFETs). Three types of materials are discussed: (1) small molecules, (2) polymers, and (3) n-doped small molecules and polymers. Much effort has been made in the modification of known building blocks, development of novel building blocks, and optimization of materials processing and device structures. These efforts have resulted in the achievement of record high electron mobilities for both small molecules (12.6 cm2 V−1 s−1) and polymers (14.9 cm2 V−1 s−1), which are approaching the highest hole mobilities achieved by p-type small molecules and polymers so far. In addition, n-doping of ambipolar and p-type organic semiconductors has proven to be an efficient approach to obtaining a greater number of n-type organic semiconductors. However, it is found that n-type organic semiconductors, in general, still lag behind p-type organic semiconductors in terms of carrier mobility and air stability. Further exploration of new building blocks for making novel materials and optimization of processing conditions and device structures are needed to improve the performance, particularly air stability.

Recent progress in the development of n-type organic semiconductors for organic field effect transistors

Insight into High-Performance Conjugated Polymers for Organic Field-Effect Transistors

Green-solvent-processable organic solar cells

One of the major challenges confronting organic electronics is the development of high-mobility semiconducting materials, especially n-channel and ambipolar semiconductors. Solution-processable semiconducting polymers have attracted much attention because of their tunable properties and their suitability for the fabrication of large-scale devices. Aza substitution has proven effective in electron-transport small-molecule semiconductors; however, high-performance polymeric semiconductors prepared by aza substitution are still lacking. We started with a computational screening procedure to introduce nitrogen atoms into isoindigo-based polymers and then proceeded with the synthesis and fabrication of field-effect transistors. The resulting 7,7′-diazaisoindigo-based polymers exhibit extensive π conjugation and high crystallinity with hole mobilities exceeding 7 cm2 V–1 s–1 with bottom-gate/bottom-contact configuration and ambipolar transport properties with top-gate/bottom-contact configuration in air. These ...

Diazaisoindigo-Based Polymers with High-Performance Charge-Transport Properties: From Computational Screening to Experimental Characterization

Direct arylation polymerization: A guide to optimal conditions for effective conjugated polymers

The electron deficiency and trans-planar conformation of bithiazole is potentially beneficial for the electron-transport performance of organic semiconductors. However, the incorporation of bithiazole into polymers through a facile synthetic strategy remains a challenge. Herein, 2,2′-bithiazole was synthesized in one step and copolymerized with dithienyldiketopyrrolopyrrole to afford poly(dithienyldiketopyrrolopyrrole-bithiazole), PDBTz. PDBTz exhibited electron mobility reaching 0.3 cm2 V–1 s–1 in organic field-effect transistor (OFET) configuration; this contrasts with a recently discussed isoelectronic conjugated polymer comprising an electron-rich bithiophene and dithienyldiketopyrrolopyrrole, which displays merely hole-transport characteristics. This inversion of charge-carrier transport characteristics confirms the significant potential for bithiazole in the development of electron-transport semiconducting materials. Branched 5-decylheptacyl side chains were incorporated into PDBTz to enhance polyme...

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Yundi Jiang

Papers

Molecular Engineering of Nonhalogenated Solution-Processable Bithiazole-Based Electron-Transport Polymeric Semiconductors

A three-dimensional Pb-centered coordination framework: crystal structure and electrochemiluminescent property