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Carbazole dendrimers up to 4th generation were synthesized. They showed significantly high T(g), amorphous and stable electrochemical properties, and great potential as solution processed hole-transporting materials for OLEDs. Alq3-based green devices exhibited high luminance efficiency and CIE coordinates of 4.45 cd A(-1) and (0.29, 0.53), respectively.

A series of bifunctional oligofluorene-cored carbazole dendrimers (GnFm, n = 1–3, m = 2–3) containing carbazole dendrons up to the third generation as end-caps were synthesized and characterized as non-doped solution-processed blue-light emitters and hole transporters for organic light-emitting diodes (OLEDs). Their optical, thermal, electrochemical, and electroluminescence properties were investigated. They exhibited a strong deep-blue fluorescence with solution fluorescence quantum yields (ΦF) of around 0.91–0.99 and formed morphologically stable amorphous thin films with glass transition temperatures as high as 273 °C. As blue emitters, solution-processed OLEDs with structure of ITO/PEDOT:PSS/GnFm/BCP/LiF:Al displayed a deep-blue emission (λELem = 415 nm, CIE = 0.17, 0.11) with a maximum luminance efficiency as high as 3.79 cd A−1 and a low turn-on voltage of 4.2 V. As hole transporters, solution-processed OLEDs with structure of ITO/PEDOT:PSS/GnFm/Alq3/LiF:Al showed a bright green emission (λELem = 520 nm, CIE = 0.30, 0.54) with a maximum luminance efficiency as high as 5.63 cd A−1 and a low turn-on voltage of 2.4 V.

A series of oligoarylfluorene-cored dendrimers containing bifluorene, bis(fluoren-2-yl)benzothiadiazole and bis[5-(fluoren-2-yl)thiophen-2-yl]benzothiadiazole as fluorescent cores, and third generation carbazole dendrons as end-caps were synthesized and characterized as RGB light-emitting materials. Their photophysical, thermal, electrochemical, and electroluminescence properties as non-doped solution processed emitters and hole-transporters for OLEDs were investigated. They displayed a bright RGB fluorescence and could form morphologically stable amorphous thin films with glass transition temperatures as high as 338 °C. Simple structured solution-processed OLEDs using these dendrimers as hole-transporting non-doped emitters emitted stable RGB colors (λELmax = 415, 521 and 622 nm) with high luminance efficiencies (up to 9.12 cd A−1 at 3.9 mA cm−2). The CIE coordinates of emitted colors were (0.63, 0.36) for red, (0.27, 0.62) for green and (0.17, 0.11) for blue, which are close to the pure RGB colors. The bifluorene-cored dendrimer as a bifunctional material showed great ability as a hole-transporting material for Alq3-based green OLEDs with a high luminance efficiency (5.63 cd A−1). Solution-processed WOLEDs based on these three dendrimers exhibited a high luminance efficiency (3.06 cd A−1 at 17.4 mA cm−2) with a high color rendering index (CRI) of 97.

Bis(fluorenyl)benzothiadiazole-cored carbazole dendrimers show high thermal and electrochemical stability, and great potential as solution processed hole-transporting non-doped green emitters for OLEDs. A pure green device with CIE coordinates of (0.27, 0.62) and high luminance efficiencies (up to 10.01 cd A(-1)) is achieved, respectively.