4nπ Stable Multitasking Azapentacene: Acidochromism, Hole Mobility, and Visible Light Photoresponse

Abstract

Herein, we describe the synthesis, characterization, and optoelectronic investigation of a stable 4nπ dihydrotetraazapentacene derivative. The neutral dihydrotetraazapentacene contains a 24π-conjugated N-heteroacene core with two phenyl pendants appended thereof. The exceptional stability of this formally antiaromatic π-system is attributed to the fused dihydropyrazine ring, which has ethenamine (enamine) conjugations, and hence, the π-electrons delocalize over the nearly planar azapentacene core to endow with a global aromatic characteristic. The embedded dihydropyrazine also offers an additional Clar's sextet with enhanced aromaticity. The present dihydrotetraazapentacene can be considered as a multitasking N-heteroacene, which showed photoresponsive nature under visible light illumination, acidochromism in solution, and p-type charge transport with an appreciable field-effect hole mobility of 0.02 cm 2 V −1 s −1 and a bulk p-type mobility of 0.98 × 10 −4 cm 2 V −1 s −1 in the space charge-limited regime of operation measured in the hole-only device. Nucleus-independent chemical shift calculation, anisotropy of the induced current density plot, and anisotropic mobility calculation were performed to support the experimental findings.

Molecular Design Concept for Enhancement Charge Carrier Mobility in OFETs: A Review

“…Generally, OFETs can be categorized into three types: p-type (hole transport), n-type (electron transport), and ambipolar (both hole and electron transport) [20]. The classification of OFETs is primarily based on the properties of the organic semiconductor layer [21][22][23][24][25][26]. The development of n-type and ambipolar OFETs is lagging behind that of p-type OFETs.…”