Highly efficient non-doped deep-blue organic light-emitting diodes based on anthracene derivatives

Abstract

Three deep-blue-emitting anthracene derivatives, 2-tert-butyl-9,10-bis(9,9-dimethylfluorenyl) anthracene (TBMFA), 2-tert-butyl-9,10-bis[4-(2-naphthyl)phenyl] anthracene (TBDNPA), and 2-tert-butyl-9,10-bis[4-(9,9-dimethylfluorenyl)phenyl] anthracene (TBMFPA), with naphthalene or 9,9-dimethylfluorene side units, have been designed, synthesized, and characterized. The anthracene derivatives show strong deep-blue emission both in solution and in thin films. The three derivatives also have high glass-transition temperatures (T_g ≥ 133 °C) due to the presence of sterically congested terminal groups. Organic light-emitting diodes (OLEDs) prepared using these anthracene derivatives as non-doped emitters exhibit bright and saturated deep-blue emissions. OLEDs based on TBDNPA give the best performance with a low turn-on voltage (3.0 V with a brightness of 1 cd m⁻²), and a high efficiency (5.17% external quantum efficiency at 8.4 mA cm⁻²). These results are among the best ever reported for saturated deep-blue OLEDs with a CIE coordinate of y < 0.10.