Coherently degenerate state engineering of organic small molecule materials to generate Wannier excitons

Abstract

Engineering organic small molecule materials capable of generating Wannier excitons is a pinnacle of research for organic optoelectronic devices. In this work, we used a coherently degenerate state strategy to design and synthesize an organic small molecule dimer compound consisting of two triphenylamine based monomers. A technique was developed to identify the coherently degenerate states in the dimer compound from the results of density functional theory calculations of. The time-resolved fluorescence measurements showed that the lifetime of the Wannier excitons in the newly designed dimer compound is less solvent dependent than that of the Frenkel excitons in the monomer. The power conversion efficiency of the photovoltaics constructed using this new material increases by 8-fold in comparison to that using the monomer. The method developed here offers extraordinary opportunities for rational design of organic materials to generate Wannier excitons.

Keywords

• Wannier exciton
• Frenkel exciton
• Coherent degeneracy
• Density functional theory
• Organic small molecule dimer
• Photovoltaics