Spirotriphenylamine based star-shaped D-A molecules meeting AIE chromophore for both efficient solution-processed doped and nondoped blue organic light-emitting diodes

To explore the structure-property of donor-acceptor (D-A) type blue emitter, in this contribution, four star-shaped compounds of p -TPA, m -TPA, p -TPA-TPE and m -TPA-TPE using spirotriphenylamine as the donor unit and triazine as the acceptor core were designed and prepared. The tetraphenylethene (TPE) unit was introduced into the D-A molecules to enhance the emission efficiency in solid state. The photophysical properties of all compounds were comparatively studied through experimental and theoretical methods. All these D-A compounds displayed blue emission (443–487 nm) both in solution and neat film. Compared to p -TPA and m -TPA, p -TPA-TPE and m -TPA-TPE possessed clear aggregated-induced emission (AIE) property and higher emission efficiency in the solid state. Both the doped and non-doped organic light-emitting diodes (OLEDs) based on m -TPA and m -TPA-TPE were fabricated by solution-processable approach. The m -TPA-TPE based non-doped device showed a satisfying performance with a high current efficiency of 4.2 cd/A and an external quantum efficiency of 1.8% in the bluish-green region. This research demonstrates that integrating AIE unit into D-A molecule is an effective strategy for design high efficient blue emitter in non-doped OLEDs.