Record‐High Electron Mobility Exceeding 16 cm<sup>2</sup> V<sup>−</sup><sup>1</sup> s<sup>−</sup><sup>1</sup> in Bisisoindigo‐Based Polymer Semiconductor with a Fully Locked Conjugated Backbone
Weifeng Zhang, Keli Shi, Jing Lai, Yankai Zhou, Xuyang Wei, Qian Che, Jinbei Wei, Liping Wang, Gui Yu
Abstract
Abstract Polymer semiconductors with mobilities exceeding 10 cm 2 V − 1 s − 1 , especially ambipolar and n‐type polymer semiconductors, are still rare, although they are of great importance for fabricating polymer field‐effect transistors (PFETs) toward commercial high‐grade electronics. Herein, two novel donor−acceptor copolymers, PNFFN‐DTE and PNFFN‐FDTE, are designed and synthesized based on the electron‐deficient bisisoindigo (NFFN) and electron‐rich dithienylethylenes (DTE or FDTE). The copolymer PNFFN‐DTE, containing NFFN and DTE, possesses a partially locked polymeric conjugated backbone, whereas PNFFN‐FDTE, containing NFFN and FDTE, has a fully locked one. Fluorine atoms in FDTE not only induce the formation of additional CH∙∙∙F hydrogen bonds, but also lower frontier molecular orbitals for PNFFN‐FDTE. Both PNFFN‐DTE and PNFFN‐FDTE form more ordered molecular packing in thin films prepared from a polymer solution in bicomponent solvent containing 1,2‐dichlorobenzene (DCB) and 1‐chloronaphthalene (with volume ratio of 99.2/0.8) than pure DCB. The two copolymers‐based flexible PFETs exhibit ambipolar charge‐transport properties. Notably, the bicomponent solvent‐processed PNFFN‐FDTE‐based PFETs afford a high electron mobility of 16.67 cm 2 V −1 s −1 , which is the highest electron‐transport mobility for PFETs reported so far. The high electron mobility of PNFFN‐FDTE is attributed to its fully locked conjugated backbone, dense molecular packing, and much matched LUMO energy level.