of these active chromophores by a chiral 1,2 diaminocyclohexane unit also allows to
induce CD and CPL properties to the TADF emitters. As a matter of fact, enantiomers
of those molecules exhibited a mirror-image CD and a CPL signals with |g lum | value
of 9.2 Â 10
À4 in thin film state. These molecules were also successfully used as
dopant in the emissive layer of an OLED owning an orange-red emission (centered at
592 nm), and exhibiting a maximum EQE value of 12.4%. Although the authors have
demonstrated the circular polarization of the emitters’ photoluminescence in thin film
state, no information was given concerning the potential circular polarization of the
light emanating from the constructed OLED devices.
13.3.3 TADF Molecules Possessing Planar Chirality
At the end of 2018, a fourth molecular design allowing to merge TADF and CPL
properties in a small molecule has been reported by Cui-Hua Zhao et al. [20] In the
first three examples of CPTADF molecules described in this chapter, the HOMOLUMO spatial separation requisite for TADF activity was attained using D-A
chromophores possessing a highly twisted relative conformation. Here, in order to
obtain a molecule owning a small exchange integral between the two frontier
orbitals, they have embedded a Donor and an Acceptor units in a chiral[2.2]paracyclophane skeleton (see Fig. 13.8).
N
N
O
O
O
O
N
N
(+)-(S,S)-8
Fig. 13.7 Chemical structure of the red CPTADF emitter described by Chen et al
Fig. 13.8 Paracyclophane based CPTADF molecules designed by Zhao et al
13 Design of Circularly Polarized Thermally Activated Delayed Fluorescence Emitters
303
induce CD and CPL properties to the TADF emitters. As a matter of fact, enantiomers
of those molecules exhibited a mirror-image CD and a CPL signals with |g lum | value
of 9.2 Â 10
À4 in thin film state. These molecules were also successfully used as
dopant in the emissive layer of an OLED owning an orange-red emission (centered at
592 nm), and exhibiting a maximum EQE value of 12.4%. Although the authors have
demonstrated the circular polarization of the emitters’ photoluminescence in thin film
state, no information was given concerning the potential circular polarization of the
light emanating from the constructed OLED devices.
13.3.3 TADF Molecules Possessing Planar Chirality
At the end of 2018, a fourth molecular design allowing to merge TADF and CPL
properties in a small molecule has been reported by Cui-Hua Zhao et al. [20] In the
first three examples of CPTADF molecules described in this chapter, the HOMOLUMO spatial separation requisite for TADF activity was attained using D-A
chromophores possessing a highly twisted relative conformation. Here, in order to
obtain a molecule owning a small exchange integral between the two frontier
orbitals, they have embedded a Donor and an Acceptor units in a chiral[2.2]paracyclophane skeleton (see Fig. 13.8).
N
N
O
O
O
O
N
N
(+)-(S,S)-8
Fig. 13.7 Chemical structure of the red CPTADF emitter described by Chen et al
Fig. 13.8 Paracyclophane based CPTADF molecules designed by Zhao et al
13 Design of Circularly Polarized Thermally Activated Delayed Fluorescence Emitters
303