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.