Molecular Modification Of 2,7-Diphenyl[1]Benzothieno[3,2-B]Benzothiophene (Dph-Btbt) With Diarylamino Substituents: From Crystalline Order To Amorphous State In Evaporated Thin Films

Introduction of diarylamino substituents on 2,7-diphenyl[1]-benzothieno[3,2-b]benzothiophene (DPh-BTBT) caused morphological change in the evaporated thin-film state: from highly crystalline films with edge-on molecular orientation for DPh-BTBT to amorphous films for the diarylamino derivatives. The former was unsuitable as a hole-transporting layer in organic light-emitting diodes (OLEDs), whereas the latter acted as a superior hole-transporting layer in multilayered OLEDs.