A Concise and Efficient Route to Electron‐Accepting 2,2′‐[2,2′‐Arenediylbis(11‐oxoanthra[1,2‐b]thiophene‐6‐ylidene)]dipropanedinitriles

Abstract

A concise organolithium‐free route to build electron‐accepting molecules consisting of two 2‐(11‐oxoanthra[1,2‐b]thiophen‐6‐ylidene)propanedinitrile units connected by functionalized π‐conjugated linkers was developed. Annulation of two thiophene rings in one step was achieved through chemoselective cyclocondensation of a bis(ethynylanthraquinone) substrate with sodium sulfide. Finally, electron‐accepting dicyanomethylene moieties were introduced by Knoevenagel condensation with malodinitrile. The synthesized 2,2′‐[2,2′‐arenediylbis(11‐oxoanthra[1,2‐b]thiophene‐6‐ylidene)]dipropanedinitriles were studied by UV/Vis and fluorescence spectroscopy, cyclic voltammetry, and DFT calculations. The acceptor properties of these compounds were confirmed by efficient light‐induced electron transfer in their blend with a donor polymer, poly(3‐hexylthiophene‐2,5‐diyl), detected by electron paramagnetic resonance spectroscopy.

Synthesis, Characterization and Photovoltaic Properties of Electron‐Accepting (11‐Oxoanthra[2,1‐b]thiophen‐6‐ylidene)dipropanedinitrile‐Based Molecules

“…Previously, we synthesized two groups of π-conjugated acceptor small molecules 1,2 (Figure 1) that differ in the structure of AT frameworks (angular or linear), the number of dicyanomethylene substituents (two or four), and the central arene linker (benzene or fluorene). [17,18] OSCs fabricated under air environment using molecule 1 a with the linear A[2, 3-b]T frameworks as an acceptor and PCDTBT as a donor polymer showed PCEs of just 0.71 %. [18] Unfortunately, the PCE of similar devices with acceptor molecule 2 a based on the angular A[1,2b]T frameworks was significantly lower, not exceeding 0.047 %.…”