Luminescence Study of DPAC-PCN Doped in Isomeric Host Materials

The rational design of thermally activated delayed fluorescence (TADF) emitters and their associated host materials has become a critical research frontier in organic light-emitting diode (OLED) technology. In this work, the influence of isomeric host materials on the luminescent properties of donor-acceptor (D-A)-type TADF emitter DPAC-PCN is investigated. Molecular dynamics simulation was performed to obtain the morphological structures of doped films, and the quantum mechanics/molecular mechanics (QM/MM) method was employed to calculate the excited state properties. The results demonstrate that host 3CzAcPy leads to a larger energy gap and a shorter emission wavelength of DPAC-PCN compared to its isomeric 9CzAcPy. In the DPAN-PCN:3CzAcPy-doped film, different residues show various luminescent properties, which may affect the luminescence purity of the OLEDs. In contrast, the luminescence of residues in the DPAN-PCN:9CzAcPy-doped film is similar to each other. This study indicates that the luminescence properties of DPAC-PCN are highly sensitive to the host material and provide a theoretical foundation for selecting an optimal host material for DPAC-PCN.