Curved Polar Dibenzocoronene Estersand Imides versus Their Planar Centrosymmetric Homologs: Photophysicaland Optoelectronic Analysis

Isomeric columnar liquid crystalline dibenzo[a,j ]coronene-tetracarboxylic tetraesters and bisimides that differ only by having either a centrosymmetric bis-peri or a polar bis-ortho substitution pattern, exhibit striking differences in the makeup of their elec- tronic ground and excited states, as well as in their performance as emitters in elec- troluminescent diodes. Quantum chemical calculations show that the key molecular orbitals consist essentially of perylene-like ones responsible for the longest-wavelength absorptions, and coronene-like ones responsible for the very intense shorter-wavelength absorptions, with modifications in particular for the ortho-imide due to its pronounced deviation from planarity. Additionally, the ortho-imide and ortho-ester, which tend to a slipped-stacked configuration within their columns due to their non-planarity, strongly outperform their peri-counterparts as emitters in organic light emitting diodes.