Facilitating intrinsic delayed fluorescence of conjugated emitters by inter-chromophore interaction.

Delayed fluorescence (DF) is a unique emitting phenomenon of great interest for important applications in organic optoelectronics. In general, DF requires well-separated frontier orbitals, inherently corresponding to charge transfer (CT)-type emitters. However, facilitating intrinsic DF for local excited (LE)-type conjugated emitters remains very challenging.

Ultrafast photophysics of -substituted 2,5-bis(arylethynyl) rhodacyclopentadienes: thermally activated intersystem crossing.

2,5-Bis(phenylethynyl) rhodacyclopentadienes (RCPDs), as a type of Rh(iii) complex, exhibit unusually intense fluorescence and slow intersystem crossing (ISC) due to weak metal-ligand interactions. However, details on their ultrafast photophysics and ISC dynamics are limited. In this work, electronic relaxation upon photoexcitation of two substituted RCPDs with two -COMe (A-RC-A) or -NMe/-COMe (D-RC-A) end groups are comprehensively investigated using femtosecond transient absorption spectroscopy and theoretical analysis.

Ultrafast photophysics of an orange-red thermally activated delayed fluorescence emitter: the role of external structural restraint.

The application of thermally activated delay fluorescence (TADF) emitters in the orange-red regime usually suffers from the fast non-radiative decay of emissive singlet states (), leading to low emitting efficiency in corresponding organic light-emitting diode (OLED) devices. Although has been quantitatively described by energy gap law, how ultrafast molecular motions are associated with the of TADF emitters remains largely unknown, which limits the development of new strategies for improving the emitting efficiency of corresponding OLED devices. In this work, we employed two commercial TADF emitters (TDBA-Ac and PzTDBA) as a model system and attempted to clarify the relationship between ultrafast excited-state structural relaxation (ES-SR) and .