D–A Solid Emitter with Crowded and Remarkably Twisted Conformations Exhibiting Multifunctionality and Multicolor Mechanochromism

Multifunctional
and mechanochromic optoelectronic materials are
of significant importance in both academic and technical aspects.
In this contribution, a novel D–A conjugate (AN2TPAN), consisting
of arylamine and two triphenylacrylonitrile (TPAN) units, with sterically
crowded and remarkably twisted conformations, has been carefully designed
and synthesized. It shows typical intramolecular charge transfer,
aggregation-induced emission, and aggregation-enhanced two-photon
absorption characteristics. Moreover, it exhibits more than three
emission colors in the solid state upon mechanical grinding. Such
multicolor mechanochromism for solid emitters under mild conditions
is rarely reported. A multilayer nondoped OLED device of AN2TPAN is
fabricated and performs excellently, whose maximal current and external
quantum efficiencies are as high as 10.7 cd/A and 3.3%, respectively.
The multifunctionality and multicolor mechanochromism of AN2TPAN make
it promising in optoelectronic applications.