CPL calculations of [7]helicenes with alleged exceptional emission dissymmetry values

Abstract

Any device based on materials exhibiting circularly polarized luminescence (CPL) requires a high degree of circular polarization, quantified through the dissymmetry factor g_lum and related quantities such as the CPL brightness. However, maximizing |g_lum| is not an easy task. For a given chiral scaffold, for example, helicenes, g_lum is usually confined below a certain threshold (e.g. 10⁻³–10⁻²). Computational tools able to predict dissymmetry values in an accurate way are therefore of utmost importance. Intrigued by exceptionally high |g_lum| values reported for two 1,1′-bitriphenylene-based [7]helicenes, we tested time-dependent density functional theory (TD-DFT) including solvation effects in predicting these large g_abs and g_lum values, in comparison with a reference [7]helicene. The quality of our results is discussed in comparison with a literature dataset.