Molecular Modulation Based on the Terminal Substituent in Twistacenes for Organic Light-Emitting Diodes

Three novel end-capping twistacene derivatives with phenyl (PyDP), naphthyl (PyDN), and anthryl groups (PyDA) have been designed and synthesized. Given the crystallographic analyses, the as-prepared molecules exhibited a twisted topological structure with the torsion angles of 35.99 degrees for PyDP and 45.85 degrees for PyDA. In addition, there is no pi-stacking interaction in PyDP. However, PyDA displayed pi-stacking interactions between the terminal intermolecular anthracene groups. The electroluminescent performance of OLEDs shows that devices with PyDP and PyDA outperform the PyDN-based device, which is attributable to their higher fluorescence quantum yields. The maximum EQE value for PyDP reaches 3.10%, which illustrates that the terminal substituent can affect the performance of OLEDs to a certain extent.