The latest progress on semiconducting applications of hexaarylbenzene is reviewed, including a fundamental overview of geometry, synthetic methods, structure-property relationship, design strategies and electronic applications in OFET, OLED and OPV.

Highly π-extended butterfly-shaped triarylamine dyads with aryleneethynylene spacer were constructed using an efficient synthetic route. These aryleneethynylenebridged dyads are highly fluorescent and exhibited high HOMO levels, and low bandgaps, which are suitable for high-performance p-type OFETs. The field-effect transistors were fabricated through a solution-processable method and exhibited promising p-type performance with fieldeffect mobility up to 4.3 cm 2 /Vs and high I on/off of 10 8 under ambient conditions.

Facile and efficient solution-processed bottom gate top contact organic field-effect transistor was fabricated by employing the active layer of picene (donor, D) and N,N′-di(dodecyl)-perylene-3,4,9,10-tetracarboxylic diimide (acceptor, A). Balanced hole (0.12 cm2/Vs) and electron (0.10 cm2/Vs) mobility with Ion/off of 104 ratio were obtained for 1:1 ratio of D/A blend. On increasing the ratio of either D or A, the charge carrier mobility and Ion/off ratio improved than that of the pristine molecules. Maximum hole (µmax,h) and electron mobilities (µmax,e) were achieved up to 0.44 cm2/Vs for 3:1 and 0.25 cm2/Vs for 1:3, (D/A) respectively. This improvement is due to the donor phase function as the trap center for minority holes and decreased trap density of the dielectric layer, and vice versa. High ionization potential (− 5.71 eV) of 3:1 and lower electron affinity of (− 3.09 eV) of 1:3 supports the fine tuning of frontier molecular orbitals in the blend. The additional peak formed for the blends at high negative potential of − 1.3 V in cyclic voltammetry supports the molecular level electronic interactions of D and A. Thermal studies supported the high thermal stability of D/A blends and SEM analysis of thin films indicated their efficient molecular packing. Quasi-π–π stacking owing to the large π conjugated plane and the crystallinity of the films are well proved by GIXRD. DFT calculations also supported the electronic distribution of the molecules. The electron density of states (DOS) of pristine D and A molecules specifies the non-negligible interaction coupling among the molecules. This D/A pair has unlimited prospective for plentiful electronic applications in non-volatile memory devices, inverters and logic circuits.

A series of new anthracene/pyrene functionalized triarylaminebased D-π-D' semiconductors are demonstrated as p-channel material for high-performance OFETs. The introduction of electron-donating end-caps and ethynyl styrylene bridged spacers at D-π-D' architecture modulated the self-ordering, electron distribution, and field-effect mobility. These molecules exhibited high-lying HOMO of ~4.8 eV, enabling the holetransporting property and reducing the energy barrier for charge injection. Organic field-effect transistors fabricated on bottom-gated top-contact architecture containing pyrene endcapped triarylamines with tert-butylphenyl sidearm as active layer displayed high hole mobility of 2.5 cm 2 /Vs and on/off current ratio of 10 7 , and the threshold voltage of À 7 V. The highest performance was supported by the molecular order of the film, planarity, high HOMO, and electron-donating nature of the end-capping units, as illustrated by the SEM, XRD, and DFT studies.