AIE-active deep red/near-infrared electroluminescent emitters with fine regulation of excited state

Abstract

Deep red/Near-infrared (DR/NIR) emitters with high photoluminescent quantum yield (PLQY) in the aggregate state are still challenge for achieving highly efficient non-doped organic light emitting diodes (OLEDs). Herein, weutilizethemethodologyofregulatingexcited-state property toadjusttheproportionof radiative and nonradiativetransitionataggregation, three aggregation-inducedemission(AIE)activeemitters (TNZNp, TNZTPAN and TNZTPEDA) withdiversesumof benzene ring rotors areprepared. TNZTPEDA with more rotors suffers from fast nonradiative transition which leads to the low fluorescent efficiency in the unimolecular and aggregate levels. Oppositely, decreasing rotors to enhance obviously solid-state PLQY of TNZNp, but the radiative transition rate is still lower than the nonradiative rate. After introducing rotational electronic donor to improving locally excited-state proportion and suppress intermolecular interaction, simultaneously, TNZTPAN has the best PLQY of 56 % due to the faster radiative transition than nonradiative transition at aggregation. Three emitters are used to manufacture non-doped OLEDs, TNZTPAN shows the maximal electroluminescence peaking at 692 nm with Commission International de L’Eclairage coordinates of (0.68, 0.30), the external quantum efficiency of 3.54 % represents a higher level among the reported non-doped DR/NIR-type OLEDs. The results of this work demonstrate the feasibility of regulating excited-state property to prepare highly bright emitters, which plays important role in designing organic DR/NIR emitters with high fluorescent efficiency at aggregation in the future.