Unveiling the relationship between the phosphorescent quantum yield and structural modification to construct high-performance Pt(II) complex

Abstract

The rigidity of the geometric structure between singlet states and triplet states is an essential factor in determining the phosphorescent quantum yield of the organometallic complexes. In this work, using NHC-platinum(II)-bdiketonate ([Pt(C^C*)(acac)] (acac = acetylacetone)) as the parent molecule, we employed chemical modifications with several electrophilic and nucleophilic functional groups, to reveal the relationship of the rigidities and phosphorescent quantum yield via density functional theory (DFT) and time-dependent density functional theory (TD-DFT). To make thorough understanding of the luminescent properties, the electronic structures, emission properties and nonradiative decay processes were all calculated. Here, The selected electron withdrawing groups actively restrain the structural distortion, enabling a high-performance Pt(II) complex. Electron donating groups (Pt-2 and Pt-4) do not change the luminescent properties of the parent species. The mechanism for the modification of the π-electronic character of the substituent can provide an alternative strategy for designing organic phosphorescent molecules for luminescent materials applications.