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

Abstract

Herein, two bis­(dicyanomethylene)-substituted quinoidal molecules QBDT and QTBDT-3H 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 QTBDT-3H was confirmed by DFT calculation, variable-temperature NMR, electron spin resonance (ESR), and superconducting quantum-interfering device (SQUID). The open-shell character enables QTBDT-3H 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.

Small-molecule ambipolar transistors

“…9) 299 and benzo[1,2- b :4,5- b ′]dithiophene ( QBDT ). 300 The charge-carrier type of the QDTBDT compounds is tuned by changing the branching position of the alkyl chains and the solution concentration of the spin-coating method. 299 QBDT has a stable open-shell ground state and exhibits typical properties of the quinoidal and biradical border, enabling the ambipolar characteristics under ambient conditions with highly balanced hole and electron mobilities of 0.16 and 0.32 cm 2 V −1 s −1 , respectively.…”

“…299 QBDT has a stable open-shell ground state and exhibits typical properties of the quinoidal and biradical border, enabling the ambipolar characteristics under ambient conditions with highly balanced hole and electron mobilities of 0.16 and 0.32 cm 2 V −1 s −1 , respectively. 300…”

Essential Role of Triplet Diradical Character for Large Magnetoresistance in Quinoidal Organic Semiconductor with High Electron Mobility

“…Unlike other diradical semiconductor materials, which show either ambipolar or p‐type transport properties, [ 34–38 ] DTBDTCN exhibited n‐type transport property. Moreover, all the devices showed similar performance in air and under an N 2 atmosphere, indicating the high ambient stability of DTBDTCN devices owing to the deep LUMO energy level.…”

“…[ 30–33 ] In OFETs, diradicaloids often show ambipolar conduction due to the low band gaps, although monopolar conduction has also been reported. [ 34–38 ] The highest hole and electron mobilities reported for OFETs based on diradical semiconductors are 1.4 [ 35 ] and 0.32 cm 2 V −1 s −1 , [ 38 ] respectively. The high mobility has been ascribed to the enhanced intermolecular interaction through the singlet states of diradicaloids.…”

Rapid Computational Approach Towards Designing Singlet-Fission Chromophores by Tuning the Diradical Character of Heteroatom-Doped Polycyclic Aromatic Hydrocarbons Using the Atom-Specific Fukui Function

“…These observations are consistent with the fact that smaller magnitudes of ΔE H−L endow the molecules with a higher diradical character and hence a more favorable thermodynamic driving force for SF. 33,79,80 In the case of aza-anthanthrene molecules, those that lie in the narrow range of ΔE H−L ∼ 2.86−2.88 eV are suitable for an isoergic SF process, whereas the ones above this range may present an endothermic situation of SF.…”