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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 is 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 cm2V−1 s−1. [ABSTRACT FROM AUTHOR]

Two acceptor small molecules consisting of 2‐(11‐oxoanthra[2,1‐b]thiophen‐6‐ylidene)dipropanedinitrile frameworks connected by a bis(thiophen‐2‐ylethynyl)arene bridge were synthesized by the two‐step sequence of Sonogashira cross‐coupling and Knoevenagel condensation in order to investigate their performance as non‐fullerene acceptors in organic solar cells. Optical, electrochemical and photovoltaic properties of new 2,2′‐[2,2′‐(5,5′‐(arenediyl)bis(ethyne‐2,1‐diyl)bis(thien‐5,2‐diyl))bis(11‐oxoanthra[2,1‐b]thiophen‐6‐ylidene)]dipropanedinitriles and previously studied analogs of 2,2′‐[2,2′‐arenediylbis(11‐oxoanthra[1,2‐b]thiophene‐6‐ylidene)]dipropanedinitriles were compared to assess the effect of introducing ethynylthiophene units between the arene linker and the 2‐(11‐oxoanthrathiophen‐6‐ylidene)propanedinitrile units. Despite the proper energy level alignment and morphology, composites of the newly synthesized compounds with the PBDB‐T donor polymer demonstrate a moderate PCE of 0.54 %. The small value of the short circuit current as compared to composites with fullerene acceptors is probably due to the low electron mobility in the newly synthesized compounds. The low electron mobility, in turn, is probably cause by the LUMO localization at the edge units of the acceptor‐type molecules, in contrast to the almost uniform LUMO delocalization over the whole π‐conjugated system for high‐performing non‐fullerene acceptors such as ITIC. [ABSTRACT FROM AUTHOR]