Novel imidazole-alkyl spacer-carbazole based fluorophores for deep-blue organic light emitting diodes: Experimental and theoretical investigation

A series of fluorescent emitters based on Imidazole-Alkyl spacer-Carbazole were designed and synthesized by connecting donor and acceptor moieties through alkyl spacer. In these design strategy we have chosen carbazole as electron rich and imidazole as electron deficient with deferent functional black (phenyl and phenyl substituted) at the N1 position of imidazole moiety. All the fluorophores were structurally confirmed by spectroscopic methods (NMR, MASS, and FTIR). The photophysical, electrochemical and electroluminescence properties were thoroughlyexamined. All the fluorophores showed good thermal stability and near-UV emission with high photoluminescence quantum yield (PLQY)of similar to 59% in the solid state. All the synthesized compounds feature Commission International de L'Eclairage (CIE) coordinates of y < 0.08 for a particular doping concentration, which is very close to the National Television Standards Committee (NTSC) standard blue (0.14, 0.08). Solution-processed organic light emitting diode (OLED) device consisting of molecule BIPOCz displays a maximum external quantum efficiency EQE of 1.9% with CIE coordinates of (0.17, 0.07). All these results reveal that this work provides novel approaches for realizing ultra-deep-blue emission with high performance.

Automated summary

A series of novel fluorescent emitters based on Imidazole-Alkyl spacer-Carbazole were designed and synthesized, showing high thermal stability and high photoluminescence quantum yield in the solid state. One of the molecules exhibited a maximum external quantum efficiency of 1.9% in OLED devices, demonstrating good performance.