Aryl‐Bridged Thienonaphthalimides: Synthesis, Characterization and Optoelectronic Properties

Abstract

Three small molecules consisting of thieno‐fused naphthalimide units connected via aromatic linkers were synthesized to study the effect of fused thiophene rings on the properties of naphthalimide‐based molecules. A protocol for the synthesis of thienonaphthalimide‐based molecules without prior preparation and use of thienonaphthalimide precursors and organoelement compounds (organolithium, organotin, or organoboron compounds) was developed. The protocol based on double thienannulation of bis‐alkyne substrates with sodium sulfide. The thin‐film morphology, photophysical and electrochemical properties of the obtained small molecules were studied. Single‐layer non‐doped organic light‐emitting diodes based on fluorene‐bridged thienonaphthalimide dimer showed yellow emission with luminance of 2200 cd/m2, and current efficiency of 0.35 cd/A. Combination of transient electroluminescence and photo‐CELIV methods allowed to estimate electron and hole mobility in the synthesized compounds; both are in order of 10‐6 cm2/V‐1s‐1.