Thermally activated delayed fluorescence dendrimers with strategic dendrons to construct highly efficient solution-processed OLEDs.

[Display omitted] • Two TADF dendrimers with the different strategic dendrons have been designed and synthesized. • The peripheral dendrons were regulated and optimized to restrain the ACQ effect and balance the carrier-transporting capability. • The G-O-mCP-based device can afford a high TADF-OLED by all solution-process with EQE of 19.98 %. • The formation of the interfacial exciplex endows the solution-processed device with the extremely low V on of 2.7 V. For the promising merits of the precise molecular structures and the satisfactory dissolvability, Thermally activated delayed fluorescence (TADF) dendrimers are turning into the attractive candidates for fully solution-processed organic light-emitting diodes (OLEDs). However, the rational design of TADF dendrimers with strategic dendrons for improving the efficiency and decreasing efficiency roll-off is still challenging. Here, two TADF dendrimers, (4S,5R)-2,4,5,6-tetrakis(4-((6-((9-(3-(9H-carbazol-9-yl)phenyl)-9H-carbazol-3-yl)oxy)hexyl)oxy)-9H-carbazol-9-yl)isophthalonitrile (G-O-mCP) and (4S,5R)-2,4,5,6-tetrakis(4-((6-(3,5-bis(1-phenyl-1H-benzo[d]imidazol-2-yl)phenoxy)hexyl)oxy)-9H-carbazol-9-yl)isophthalonitrile (G-O-DPBi) were developed and synthesized by integrating the peripheral strategic dendrons with the emissive core through nonconjugated alkoxy chains. Impressively, the peripheral dendron of G-O-mCP possessing the superior hole-transporting capability belongs to the electron-donor category and the peripheral dendron of G-O-DPBi with the admirable electron-transporting capability belongs to the electron-acceptor category. The elaborate regulation of the different dendrons with solubilizing groups is beneficial for restraining the aggregation-caused quenching (ACQ) effect and balancing the carrier transport capability. Consequently, the fully solution-processed device based on G-O-mCP realized the maximum external quantum efficiency (EQE) of 19.98 %. In addition, the formation of the interfacial exciplex endows the solution-processed device with a extremely low turn-on voltage (V on) of 2.7 V and a high power efficiency (PE) of 43.80 lm/W, which is among the highest power efficiency of the reported TADF-OLEDs. [ABSTRACT FROM AUTHOR]