appear as a solution of choice to build more efficient OLED devices. But because of
the atypical conditions that are required to generate such a delayed fluorescence:
small ΔE ST , high ISC, and RISC probabilities along with rather long T 1 lifetime,
efficient TADF emitters are difficult to design.
In order to minimize the ΔE ST in small organic molecules, one of the most
reliable approaches described so far involves the design of Donor–Acceptor (D-A)
molecules in which a steric hindrance allows to twist D and A moieties around the
D-A axis. The origin of this design rule is arising from the fact that such geometry in
D-A molecules reduces the HOMO and LUMO overlap, which is proportional to the
ΔE ST. We will see in the following lines that most of the chiral TADF molecules
developed so far adhere to this design paradigm . However, this has the potential to
reduce the oscillator strength of the transition and therefore to be detrimental to the
fluorescence quantum yield (Φ PL ). Please see references [10–12] for further information about the design of TADF molecules.
13.3 CPTADF Emitters: Design, Synthesis, Photophysical,
and Chiroptical Properties
13.3.1 TADF Molecules Possessing Point Chirality
Shuzo Hirata and co-workers were the first to report the design and synthesis of a
molecule merging both TADF and CPL properties (named CPTADF molecules for
Fig. 13.1 Simplified Perrin-Jablonski diagram
13 Design of Circularly Polarized Thermally Activated Delayed Fluorescence Emitters
295
the atypical conditions that are required to generate such a delayed fluorescence:
small ΔE ST , high ISC, and RISC probabilities along with rather long T 1 lifetime,
efficient TADF emitters are difficult to design.
In order to minimize the ΔE ST in small organic molecules, one of the most
reliable approaches described so far involves the design of Donor–Acceptor (D-A)
molecules in which a steric hindrance allows to twist D and A moieties around the
D-A axis. The origin of this design rule is arising from the fact that such geometry in
D-A molecules reduces the HOMO and LUMO overlap, which is proportional to the
ΔE ST. We will see in the following lines that most of the chiral TADF molecules
developed so far adhere to this design paradigm . However, this has the potential to
reduce the oscillator strength of the transition and therefore to be detrimental to the
fluorescence quantum yield (Φ PL ). Please see references [10–12] for further information about the design of TADF molecules.
13.3 CPTADF Emitters: Design, Synthesis, Photophysical,
and Chiroptical Properties
13.3.1 TADF Molecules Possessing Point Chirality
Shuzo Hirata and co-workers were the first to report the design and synthesis of a
molecule merging both TADF and CPL properties (named CPTADF molecules for
Fig. 13.1 Simplified Perrin-Jablonski diagram
13 Design of Circularly Polarized Thermally Activated Delayed Fluorescence Emitters
295