Construction of Efficient Deep Blue Aggregation-Induced Emission Luminogen from Triphenylethene for Nondoped Organic Light-Emitting Diodes

Deep blue emitters are crucial for full color displays and organic white lighting. Thanks to the research efforts by scientists, many efficient light emitters with aggregation-induced emission (AIE) characteristics have been synthesized and found promising applications in organic light-emitting diodes (OLEDs). However, few AIE emitters with deep blue emissions and excellent electroluminescence (EL) performance have been reported. The contribution here reports a simple but successful molecular design strategy for synthesizing efficient solid-state emitters for nondoped OLEDs with both deep blue and white emissions. This strategy utilizes triphenylethene, a weakly conjugated AIE luminogen, as building block for constructing deep blue emitter, involving no complicated control of emission color through adjustment of the steric hindrance of chromophores, and enables a wide selection of partnered functional units. The synthesized AIE luminogen, abbreviated as BTPE-PI, is thermally stable and exhibits high fluorescence quantum efficiency as well as good charge injection capability in the solid state. Nondoped deep blue OLED fabricated from BTPE-PI shows a very high external quantum efficiency of 4.4% with a small roll-off, whose performance is the best among deep blue AIE materials reported so far. An efficient white OLED with Commission Internationale de lEclairage (CIE) coordinates of (0.33, 0.33) at theoretical white point was first achieved by using AIE luminogen BTPE-PI as deep blue emitter. Such molecular design strategy opens a new avenue in the development of efficient solid-state deep blue emitters for nondoped OLED applications.