Predicting Operational Stability for Organic Light‐Emitting Diodes with Exciplex Cohosts

Abstract

Organic light‐emitting diodes (OLEDs) employing exciplex cohosts have gained attractive interest due to the promising high efficiency, low driving voltage, and potential low cost in future solid‐state lighting sources and full‐color displays. However, their device lifetime is still the most challenging weakness and rarely studied, which is regarded as a time consuming and complicated work. Therefore, a simplified but effective and comprehensive approach is demonstrated to give prediction for the exciplex cohosts operating lifespan and analyze their possible degradation mechanisms by considering molecular dissociated activation energy with internal exciton dynamics correlations. As a consequence, strong chemical bond stability for the hole transport moieties and rapid reactive exciton relaxation have the intrinsic talent to access potentially long‐lived exciplex cohosts, achieving an extended lifetime of 10169 h for the predicted long‐lived exciplex cohost OLEDs. Degradation behaviors further confirm that the deteriorated source is attributed to the formation of exciton quenchers and hole traps from excited states and charged‐excited states, respectively. The current findings establish a universal technique to screen the stable exciplex cohost candidates with economic time consumption and expenses.

Improved Efficiency and Lifetime of Deep‐Blue Hyperfluorescent Organic Light‐Emitting Diode using Pt(II) Complex as Phosphorescent Sensitizer

“…[ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ] Such TTA and TPQ in deep blue OLEDs generate highly‐energetic excited states (≥6.0 eV) that may highly likely induce chemical bond dissociation in the charge transport/exciton blocking layer and EML, resulting in a permanent decrease in device luminance. [ 5 , 11 , 16 , 17 , 18 ] Ensuring short exciton decay time and managing the exciton distribution in the EML is, therefore, of great importance to realize both long lifetime and high efficiency of deep blue OLEDs. [ 11 , 19 , 20 , 21 ]…”

Rigid Oxygen‐Bridged Boron‐Based Blue Thermally Activated Delayed Fluorescence Emitter for Organic Light‐Emitting Diode: Approach towards Satisfying High Efficiency and Long Lifetime Together

“…Here, DBA‐DI was designed to have a high BDE and to reduce the effect of long‐lived and high energy triplet excitons. [ 23–26 ] The fabricated single host TADF‐OLED exhibited maximum EQE of 28.1% and long device lifetime (LT 50 ) of 329 h. Also, the mixed host device showed a high EQE of 26.4% with a lifetime of 540 h (LT 50 at the initial luminance of 1000 cd m −2 ).…”

A π–D and π–A Exciplex‐Forming Host for High‐Efficiency and Long‐Lifetime Single‐Emissive‐Layer Fluorescent White Organic Light‐Emitting Diodes

“…Exciplexes constituted by electronrich 9,9′-diphenyl-9H,9′H-3,3′-bicarbazole (BCz) and electrondeficient of 1,3,5-triazine (TRZ) derivatives have proved to be stable with efficient RISC process [14] , which, nevertheless, only provided wide green emissions peaked at ≈500 nm. [15] The emission spectra of BCz: TRZ films were also measured here and provided in Figure S1 (Supporting Information), showing clear exciplex emission peaked at 496 nm. It has been pointed out that the exciplex emission energy can be determined by hv ex ≈ I D − A A − E C , where I D and A A stand for the donor ionization potential and the acceptor electron affinity, respectively.…”