TY - JOUR
T1 - Blue Thermally Activated Delayed Fluorescence with Sub-Microsecond Short Exciton Lifetimes
T2 - Acceleration of Triplet–Singlet Spin Interconversion via Quadrupolar Charge-Transfer States
AU - Min, Hyukgi
AU - Park, In Seob
AU - Yasuda, Takuma
N1 - Funding Information:
This work was supported in part by a Grant‐in‐Aid for JSPS KAKENHI (Grant Nos. JP21H04694, JP18H02048, and JP19K15651), JST CREST (Grant No. JPMJCR21O5), the Murata Science Foundation, and the Mitsubishi Foundation. H.M. acknowledges financial support from the JASSO Honors Scholarship. The authors are grateful for the support provided by the Cooperative Research Program “Network Joint Research Center for Materials and Devices” and the computer facilities at the Research Institute for Information Technology, Kyushu University.
Publisher Copyright:
© 2022 Wiley-VCH GmbH.
PY - 2022/7/4
Y1 - 2022/7/4
N2 - Exciton lifetime is a critical factor in determining the performance of optoelectronic functional systems and devices. Thermally activated delayed fluorescence (TADF) emitters that can concurrently achieve a high fluorescence quantum yield and short exciton lifetime are desirable for application in organic light-emitting diodes (OLEDs) with suppressed efficiency roll-off. Herein, phenoxaborin and xanthone-cored TADF emitters with quadrupolar electronic structures are reported to exhibit sub-microsecond TADF lifetimes as short as 650 and 970 ns, respectively, while preserving high fluorescence quantum yields. By extending the El-Sayed rule to the quadrupolar π-systems, the contribution of doubly degenerate charge-transfer excited states induced by dual donor units can enhance the spin–orbit coupling between them, leading to a spin-flip acceleration between the excited triplet and singlet states. This electronic feature is advantageous for mitigating exciton annihilation processes in the emission layer, thereby reducing the efficiency roll-offs in OLEDs. Consequently, a high external electroluminescence quantum efficiency over 20% can be retained, even under operating the device at a high luminance of 1000 cd m−2.
AB - Exciton lifetime is a critical factor in determining the performance of optoelectronic functional systems and devices. Thermally activated delayed fluorescence (TADF) emitters that can concurrently achieve a high fluorescence quantum yield and short exciton lifetime are desirable for application in organic light-emitting diodes (OLEDs) with suppressed efficiency roll-off. Herein, phenoxaborin and xanthone-cored TADF emitters with quadrupolar electronic structures are reported to exhibit sub-microsecond TADF lifetimes as short as 650 and 970 ns, respectively, while preserving high fluorescence quantum yields. By extending the El-Sayed rule to the quadrupolar π-systems, the contribution of doubly degenerate charge-transfer excited states induced by dual donor units can enhance the spin–orbit coupling between them, leading to a spin-flip acceleration between the excited triplet and singlet states. This electronic feature is advantageous for mitigating exciton annihilation processes in the emission layer, thereby reducing the efficiency roll-offs in OLEDs. Consequently, a high external electroluminescence quantum efficiency over 20% can be retained, even under operating the device at a high luminance of 1000 cd m−2.
UR - http://www.scopus.com/inward/record.url?scp=85130044416&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85130044416&partnerID=8YFLogxK
U2 - 10.1002/adom.202200290
DO - 10.1002/adom.202200290
M3 - Article
AN - SCOPUS:85130044416
SN - 2195-1071
VL - 10
JO - Advanced Optical Materials
JF - Advanced Optical Materials
IS - 13
M1 - 2200290
ER -