Tuning the electronic and photophysical properties of platinum(II) complexes through ancillary ligand modification: a theoretical study

Abstract

In this work, six Pt(II) complexes have been studied via density functional theory (DFT)/time-dependent DFT caculations to explore the influence of different ancillary ligand on electron structures, photophysical properties and radiative decay processes. Moreover, the self-consistent spin–orbit coupling TDDFT was used to calculate zero-field splitting, radiative rate and radiative lifetime to unveil the radiative deactivation processes for these complexes. The results indicated that [Pt(ppy)(ppz)] (ppy = 2-phenylpyridine and ppz = 5-(2-pyridyl)-pyrazole) has a higher radiative decay rate constant and a smaller nonradiative decayrate constant than that of [Pt(ppy)(acac)] (acac = acetylacetonate). Furthermore, complex 5, with dimesityboron added on the 3′-position of the pyrazole ring in [Pt(ppy)(ppz)], shows great potential to serve as an efficient blue-green light emitter in OLED.

Graphical abstract

Better phosphorescent properties can be obtained from proper alteration or modification of the ancillary ligand in cyclometalated platinum complexes.

Keywords:

• Platinum(II) complexes
• ancillary ligand
• zero-field splitting
• density functional theory
• radiative rate constant
• nonradiative decayrate constant
• OLED