Tilted Spiro‐Type Thermally Activated Delayed Fluorescence Host for ≈100% Exciton Harvesting in Red Phosphorescent Electronics with Ultralow Doping Ratio. (19th January 2018)

• Record Type: Journal Article
• Authors: Wang, Ya‐Kun; Li, Si‐Hua; Wu, Sheng‐Fan; Huang, Chen‐Chao; Kumar, Sarvendra; Jiang, Zuo‐Quan; Fung, Man‐Keung; Liao, Liang‐Sheng
• Is Part Of: Advanced functional materials. Volume 28:Number 13(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-01-19
• Subjects: doping ratios -- red emission -- resonance energy transfer -- thermally activated delayed fluorescence -- tilted spiro geometry; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201706228
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Despite promising efficiency, the high fabrication cost due to the required high concentrations of noble metal based phosphors is still problematic for phosphorescent organic light‐emitting diodes (PhOLEDs). This situation becomes even serious considering some practical applications need high luminance, which in turn requires a higher concentration of emitters. A paradigm shift to circumvent these issues can be development of materials that are able to operate efficiently in very low concentrations (< 1 wt%). Here, two thermally activated delayed fluorescence hosts (OSTFPCN andOSTFPB ) with tilted spiro geometry, small singlet‐triplet splitting (Δ E st ), and effective resonance energy transfer are developed. Within expectation, record performances with a power efficiency of 63.6 lm W −1 and an external quantum efficiency (EQE) of 31.2% for the red phosphor Ir(MDQ)2 (acac) (2.0 wt%) are achieved withOSTFPCN as host. Additionally, a high power efficiency around 58 lm W −1 is also gained even at an ultralow dopant concentration of 0.5 wt% for aOSTFPB based device. Mechanism studies demonstrate that efficiency roll‐off can be effectively suppressed in such low concentrations. These findings pave a new way to exploit low cost and high efficiency PhOLEDs. Abstract : Two tilted spiro geometry based thermally activated delayed fluorescence type hosts are developed and implemented as host for organic light‐emitting diodes. Record power efficiency of 63.6 lm W −1 and external quantum efficiency (EQE) of 31.2% for Ir(MDQ)2 (acac) based device are obtained. Notably, even under ultralow phosphor dopant concentration (0.5 wt%), high power efficiency of around 58 lm W −1 is still achievable.