page_title: Thermally activated delayed fluorescence
section_title: Organic LEDs
hierarchical_section_title: Thermally activated delayed fluorescence / Applications / Organic LEDs
caption_attribution_description: LG 4K Curved OLED TV
context_page_description: Thermally activated delayed fluorescence is a process through which a molecular species in a non-emitting excited state can incorporate surrounding thermal energy to change states and only then undergo light emission. The TADF process involves an excited molecular species in a triplet state, which commonly has a forbidden transition to the ground state termed phosphorescence. By absorbing nearby thermal energy the triplet state can undergo reverse intersystem crossing converting it to a singlet state, which can then de-excite to the ground state and emit light in a process termed fluorescence. Along with fluorescent and phosphorescent compounds, TADF compounds are one of the three main light-emitting materials used in organic light-emitting diodes.
  Another type of TADF process has been shown to originate from conformational trapping to a dark state. Thermal energy allows the repopulation of the emissive state resulting in a delayed fluorescence.
context_section_description: The vast majority of research on TADF-based materials is focused on improving the efficiency and lifetime of TADF-based OLEDs. Organic light-emitting diodes or OLEDs have provided an alternative to traditional [liquid-crystal display] (LCD) displays due to their improved contrast, response time, wider viewing angle, and the possibility of making flexible displays. The first generation of OLEDs were based on fluorescent materials, which includes most OLED or AMOLED displays that are currently commercially available. The second generation of OLED materials employ phosphorescence light emission, which has the advantage of higher theoretical efficiency, but may still be lacking in other areas like the poor lifetimes seen in phosphorescent blue emitters.
  Many consider the third generation of OLEDs to be TADF materials because of their already impressive quantum efficiencies and performance in small test devices. In practice, these newer TADF materials still have difficulties with solution processability in larger practical devices and many blue TADF molecules show poor performance and lifetimes. If these challenges can be addressed, TADF-based OLEDs show promise in replacing current LCD-based displays and OLED-based displays especially in curved televisions and flexible phone screen designs. In 2019, Taiwan-based Wisechip launched the world's first OLED display that uses TADF emitters (developed by Kyulux) in a Hyperfuorescence structure.
caption: LG 4K Curved OLED TV
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