TY - JOUR
T1 - Systematically tuning of optoelectronic properties from electron donating to accepting substituents on bicarbazole/cyanobenzene hybrids
T2 - Host to dopant materials for phosphorescent and delayed fluorescence OLEDs
AU - Cao, Xudong
AU - Zhang, Xianping
AU - Wang, Menghan
AU - Shi, Dengke
AU - Wu, Qingjing
AU - Tao, Youtian
AU - Huang, Wei
N1 - Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2018/1
Y1 - 2018/1
N2 - Six bicarbazole/cyanobenzene hybrid compounds are designed and synthesized by changing the substituents from electron-donating phenylcarbazole (PCzCNBCz, 1), phenoxy (OPCNBCz, 2) and methyl (MCNBCz, 3), neutral hydrogen (HCNBCz, 4) to electron-accepting trifluomethyl (CF3CNBCz, 5) and cyano (DCNBCz, 6) moieties, respectively at the same meta-position of cyanobenzene (refer to carbazole). The substituted units are judiciously designed with both conjugated (phenylcarbazole and cyano) and non-conjugated (phenoxy, methyl and trifluomethyl) units. Their HOMO and LUMO energy levels are rationally adjusted from 5.17 to 5.46 eV and 2.13–2.50 eV, respectively. Compared to bare hydrogen-attached 4 with triplet energy (T1) of 2.7 eV, the conjugated moiety based 1 and 6 lowered T1 to ≤2.50 eV, while other compounds bearing either non-conjugated donating or accepting units unexpectedly maintain T1 as high as ∼2.70 eV. Moreover, the singlet-triplet bandgaps (ΔEST) can also be tailored from 0.01 to 0.32 eV, therefore, delayed fluorescence characteristics are observed in the electron-accepting trifluomethyl and cyano substituted 5 and 6. The high triplet 2, 3 and 4 are served as host materials for blue phosphorescent OLEDs, with maximum external quantum efficiency (EQE) up to 20.5%, while 5 and 6 are used as sky-blue and greenish-blue emitters in delayed fluorescence OLEDs, with maximum EQE of 4.9 and 10.0%, respectively.
AB - Six bicarbazole/cyanobenzene hybrid compounds are designed and synthesized by changing the substituents from electron-donating phenylcarbazole (PCzCNBCz, 1), phenoxy (OPCNBCz, 2) and methyl (MCNBCz, 3), neutral hydrogen (HCNBCz, 4) to electron-accepting trifluomethyl (CF3CNBCz, 5) and cyano (DCNBCz, 6) moieties, respectively at the same meta-position of cyanobenzene (refer to carbazole). The substituted units are judiciously designed with both conjugated (phenylcarbazole and cyano) and non-conjugated (phenoxy, methyl and trifluomethyl) units. Their HOMO and LUMO energy levels are rationally adjusted from 5.17 to 5.46 eV and 2.13–2.50 eV, respectively. Compared to bare hydrogen-attached 4 with triplet energy (T1) of 2.7 eV, the conjugated moiety based 1 and 6 lowered T1 to ≤2.50 eV, while other compounds bearing either non-conjugated donating or accepting units unexpectedly maintain T1 as high as ∼2.70 eV. Moreover, the singlet-triplet bandgaps (ΔEST) can also be tailored from 0.01 to 0.32 eV, therefore, delayed fluorescence characteristics are observed in the electron-accepting trifluomethyl and cyano substituted 5 and 6. The high triplet 2, 3 and 4 are served as host materials for blue phosphorescent OLEDs, with maximum external quantum efficiency (EQE) up to 20.5%, while 5 and 6 are used as sky-blue and greenish-blue emitters in delayed fluorescence OLEDs, with maximum EQE of 4.9 and 10.0%, respectively.
KW - Bicarbazole
KW - Delayed fluorescence
KW - Dopant
KW - Host
KW - Phosphorescence
UR - http://www.scopus.com/inward/record.url?scp=85031037244&partnerID=8YFLogxK
U2 - 10.1016/j.orgel.2017.09.041
DO - 10.1016/j.orgel.2017.09.041
M3 - 文章
AN - SCOPUS:85031037244
SN - 1566-1199
VL - 52
SP - 22
EP - 31
JO - Organic Electronics
JF - Organic Electronics
ER -