Triazolotriazine-based thermally activated delayed fluorescence materials for highly efficient fluorescent organic light-emitting diodes (TSF-OLEDs)

Molecular design of thermally activated delayed fluorescent emitters for narrowband orange–red OLEDs boosted by a cyano-functionalization strategy

“… 4 The intramolecular charge-transfer (ICT) characteristic in the twisted D–A structure provides the TADF material the advantage of easily achieved full-color emission, and thus a large number of TADF materials have been developed in the past decade. 5 However, the twisted D–A molecular structures inevitably cause significant vibronic coupling between the ground state (S 0 ) and the excited singlet state (S 1 ) as well as remarkable structure relaxation of S 1 . 6 Consequently, TADF materials have broad emission spectra with a full-width at half-maximum (FWHM) as large as 100 nm, which cannot satisfy the requirement of high color purity in high-resolution displays.…”

Overcoming energy loss of thermally activated delayed fluorescence sensitized-OLEDs by developing a fluorescent dopant with a small singlet–triplet energy splitting

“…Next, the expected products 67dTPA-FQ and 267tTPA-FQ could be afforded by a Suzuki coupling reaction through intermediates (1a and 1b) reacting with 4-(diphenylamino)phenylboronic acid. The two compounds were characterized and verified by 1 H and 13 C NMR spectra and high-resolution mass spectra, which are presented in the ESI. † Scheme 1 The molecular structures of 23dTPA-FQ, 67dTPA-FQ and 267tTPA-FQ, as well as the synthetic routes of the latter two compounds.…”

“…Recently, a TADFsensitizing-fluorescence (TSF) strategy has been recognized as one of the most promising technologies for solving this issue. [12][13][14][15][16] In a TSF-OLED, the light-emitting layer (EML) usually includes a host, a TADF sensitizer as well as common fluorescent dopants (FDs), in which the excitons formed on the host are firstly transferred to the TADF sensitizer and then to the final emitter FDs via the Fo ¨rster mechanism, which offers low efficiency roll-off, tunable colors and 100% exciton utilization. 11,12 Despite these many advantages, the device performance usually gets worse once FDs are introduced to the EML including the host and TADF sensitizer due to the disturbing energy loss caused by the T 1 states of the FDs, formed by Dexter energy transfer (DET) from the T 1 states of the host and the TADF sensitizer.…”

A periphery hindered strategy with a dopant and sensitizer for solution-processed red TSF-OLEDs with high color purity

“…19–23 A TADF sensitizer is responsible for 100% excitons utilization efficiency, while CFDs as the final emitters take charge of narrowband emission and high radiative efficiency. 24–26 Although TSF-based OLEDs devices have achieved excellent performance in blue, green, and yellow devices, the development of outstanding red devices is still lagging due to the energy gap law, strong non-radiative processes, and subsequent low Φ PL values. 27–30…”