Realization of exceeding 80% external quantum efficiency in organic light-emitting diodes using high-index substrates and highly horizontal emitters

Recent advances of NIR-TADF (λmaxPL/EL > 700 nm) emitters and their applications in OLEDs

“…For 12 wt% doping ratios, the λ EL was found to be 723 nm with an EQE value of 19.7%. The increment in the thickness of ETL also enhanced the Φ out into ∼41%, which was attributed to the modulation in the micro-cavity effect; 69,70 however, with the relatively long-delayed fluorescence lifetime, the device showed considerable efficiency roll-off due to the triplet excitons and triplet-involved quenching processes.…”

Highly efficient near-infrared thermally activated delayed fluorescence organic light-emitting diodes with emission beyond 800 nm

“…Compared with the PL spectra, a redshift was observed in the EL spectra at a given doping ratio, which was ascribed to the microcavity effect of the device. 28 The turn-on voltage with current density exceeding 10 −5 mA cm −2 decreased gradually from 2.2 V to 1.8 V with the increase in the doping ratio from 9 wt% to 50 wt%. Lee and coworkers reported that the high doping ratio of TADF emitters could result in enhanced and balanced carrier transport in the emitting layer.…”

An extended π-backbone for highly efficient near-infrared thermally activated delayed fluorescence with enhanced horizontal molecular orientation

“…It is well known that the modulation of the microcavity effect via tuning the thickness of the electron-transporting layer (ETL) could lead to an enhancement in optical efficiency and a red shift in emission spectra. 19 Yet, such a large red shift of 29 nm caused by the variation of the thickness of the hole-transporting layer (HTL) is less often reported. Due to the high PLQY of TPA-CN-N4, the red/dark red OLEDs showed high EQEs of over 20% photon/electron with the emission peak ranging from 652 nm to 689 nm.…”