Tuning Biradical Character to Enable High and Balanced Ambipolar Charge Transport in a Quinoidal π-System

Abstract

Herein, two bis(dicyanomethylene)-substituted quinoidal molecules <b>QBDT</b> and <b>QTBDT-3H</b> were designed and synthesized to explore the open-shell effect on tuning the charge transport behavior of organic π-functional materials. The biradical character of <b>QTBDT-3H</b> was confirmed by DFT calculation, variable-temperature NMR, electron spin resonance (ESR), and superconducting quantum-interfering device (SQUID). The open-shell character enables <b>QTBDT-3H</b> an ambipolar characteristic under ambient conditions with highly balanced electron and hole mobilities of 0.32 and 0.16 cm² V^-1 s^-1, respectively.