Development of highly efficient meridional Ir(III) complexes in solution-processed green phosphorescent organic light-emitting diodes

Two highly effective homoleptic meridional (mer) isomer-based emitters Ir(III) complexes, mer-MECF and mer-MEMO were synthesized for use in solution-processed phosphorescent organic light-emitting diodes (PHOLEDs). Both Ir(III) complexes contained a (2-ethylhexyl group) and different functional groups, such as trifluoromethyl (-CF3) and methoxy (-OCH3) and a substituted amide-bridged phenylpyridine unit, which was utilized as a main ligand. Thermal, photochemical, electroluminescence (EL) and electrochemical properties performances were examined. Interestingly, both complexes exhibited a structureless green light emission spectrum, high photoluminescence quantum yields (PLQYs) and excellent solubility in organic solvents. The solution-processed PHOLED containing mer-MEMO as dopant exhibited an excellent external quantum efficiency of 16.5 % and a current efficiency 54.3 cd A−1. The electron transport layer (ETL) optimized device containing mer-MECF as dopant had an excellent external quantum efficiency of 21.1 % and a current efficiency 71.4 cd A−1. The study shows that the described amide-bridged mer Ir(III) complexes have potential use as solution-processed PHOLEDs. [Display omitted] •Designed and synthesized two new mer homoleptic Ir(III) complexes consist of 2-ethylhexyl and different functional groups functionalized an amide-bridged phenylpyridine unit used as a main ligand, such as trifluoromethyl (-CF3) in mer-MECF and methoxy (-OCH3) in mer-MEMO for green solution-processed PHOLEDs.•These Ir(III) complexes exhibited intensive green emission (λmax= 529 and 513 nm) and high photoluminescence quantum yields (PLQYs).•EQEmax of 21.1 and 16.5 % the Lmax of 22922 and 10316 cd m−2 at 5 wt% for mer-MECF and mer-MEMO, respectively.•Our research suggest that Ir(III) complexes have a lot of potential for creating high-efficiency, pure green EL emission PHOLEDS.