TY - JOUR
T1 - Donor engineered Deep-Blue emitters for tuning luminescence mechanism in Solution-Processed OLEDs
AU - Hwang, Jinhyo
AU - Kang, Hyunchul
AU - Jeong, Ji Eun
AU - Woo, Han Young
AU - Cho, Min Ju
AU - Park, Sungnam
AU - Choi, Dong Hoon
N1 - Funding Information:
The authors acknowledge the financial support from the National Research Foundation of Korea ( NRF2019R1A2C2002647 and NRF2019R1A6A1A11044070 ) D. H. Choi particularly thanks for the support from LG Display Co. Limited ( Q1830291 ) The authors are grateful to the Institute for Basic Science (IBS, Korea) for allowing us to obtain nuclear magnetic resonance data (NMR; Ascend 500, Bruker).
Publisher Copyright:
© 2021
PY - 2021/7/15
Y1 - 2021/7/15
N2 - Three novel solution-processable A-π-2D-type deep-blue emitters, namely BCz, BBFCz, and BICz, were developed to investigate their luminescence mechanisms and performances in organic light-emitting diodes (OLEDs). The emitters were uniquely designed by connecting two carbazole analogs as donors and a boron-fused unit as an electron acceptor to the benzene core; they exhibited aggregation-induced emission properties in the film states. Theoretical calculations and time-resolved photoluminescence (TRPL) experimental results indicate that the luminescence mechanism of the three emitters changed from fluorescence to thermally activated delayed fluorescence (TADF) as the donor unit was changed from carbazole to indenocarbazole. BCz was found to act like a fluorescent emitter, but BBFCz and BICz displayed TADF characteristics. Efficient reverse intersystem crossing (RISC) in BICz was confirmed by small ΔEST, Ea, and kISC/kRISC ratio. Consequently, non-doped solution-processed TADF-OLEDs based on BICz as an emitter exhibited the highest external quantum efficiency (EQE) of 10.11%, with deep-blue commission International de ĺEclairage (CIE) color coordinates (0.16, 0.08). In contrast, BCz- and BBFCz-based devices showed relatively lower EQEs of 3.44% and 6.78%, respectively. The results showed that BICz as an emitter displayed exceptional performance in a non-doped solution-processed deep-blue TADF-OLED.
AB - Three novel solution-processable A-π-2D-type deep-blue emitters, namely BCz, BBFCz, and BICz, were developed to investigate their luminescence mechanisms and performances in organic light-emitting diodes (OLEDs). The emitters were uniquely designed by connecting two carbazole analogs as donors and a boron-fused unit as an electron acceptor to the benzene core; they exhibited aggregation-induced emission properties in the film states. Theoretical calculations and time-resolved photoluminescence (TRPL) experimental results indicate that the luminescence mechanism of the three emitters changed from fluorescence to thermally activated delayed fluorescence (TADF) as the donor unit was changed from carbazole to indenocarbazole. BCz was found to act like a fluorescent emitter, but BBFCz and BICz displayed TADF characteristics. Efficient reverse intersystem crossing (RISC) in BICz was confirmed by small ΔEST, Ea, and kISC/kRISC ratio. Consequently, non-doped solution-processed TADF-OLEDs based on BICz as an emitter exhibited the highest external quantum efficiency (EQE) of 10.11%, with deep-blue commission International de ĺEclairage (CIE) color coordinates (0.16, 0.08). In contrast, BCz- and BBFCz-based devices showed relatively lower EQEs of 3.44% and 6.78%, respectively. The results showed that BICz as an emitter displayed exceptional performance in a non-doped solution-processed deep-blue TADF-OLED.
KW - Boron acceptor
KW - Deep-blue emitters
KW - Luminescence mechanism
KW - Non-doped organic light-emitting diodes
KW - Thermally activated delayed fluorescence
UR - http://www.scopus.com/inward/record.url?scp=85102012205&partnerID=8YFLogxK
U2 - 10.1016/j.cej.2021.129185
DO - 10.1016/j.cej.2021.129185
M3 - Article
AN - SCOPUS:85102012205
VL - 416
JO - Chemical Engineering Journal
JF - Chemical Engineering Journal
SN - 1385-8947
M1 - 129185
ER -