Theoretical studies on the electronic structures and optical properties of star-shaped triazatruxene/heterofluorene co-polymers

Triazatruxene derivatives and heterofluorenes have drawn increasing attention in the applications of OLED devices due to their particular electronic structures and optical properties. To improve on the thermal and morphological stability and enhance electroluminescent (EL) efficiency, six series of star-shaped triazatruxene/heterofluorene co-polymers have been designed. To reveal structure–property relationships of the novel functional materials, an in-depth theoretical investigation was elaborated using the density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. The results HOMOs, LUMOs, ΔH–L, Eg, as well as some other electronic structures and IPs, EAs, λ, τ, the absorption and emission spectra can be tuned by the introduction of heterofluorenes into the triazatruxene core. The various properties of these co-polymers were obtained by extrapolating those of the co-oligomers to infinite chain length. It was concluded that these triazatruxene/heterofluorene co-polymers are interesting optoelectronic functional materials, which have great potential for the application in OLEDs.

► The introduction of different heterofluorenes almost has no effect on the TAT.
► TNF/TBF has better hole/electron injection/transport ability than other series.
► The conjugation enhances resulting in red-shifted absorption and emission spectra.
► TBF/other five series can be used as red/blue light-emitting materials.