Uncommon Intramolecular Charge Transfer Effect and Its Potential Application in OLED Emitters

Planarized intramolecular charge transfer(PLICT) state can facilitate the fluorescence process thanks to the relative excellent planarity. Recently, we have discovered that the excited state quinone-conformation induced planarization(ESQIP) occurring on tetraphenylpyrazine(TPP) based derivatives could furnish them with PLICT feature. Unlike to the well-known intramolecular charge transfer, strengthening the electron-donating nature on the donor(D) moiety did not impair the PLICT. The calculation results showed that planarization of the TPP based compounds scarcely accompanied with energy wastage while amount of energy was required for the torsion on geometries. In the polar solvents, the energy consumption for planarization could further decrease, but that for twisting structure would increase. To take advantage of the transformation of the frontier orbitals’ distribution, the PLICT type materials would perform a potential application on organic light-emitting diodes(OLEDs).