Conjoint use of Dibenzosilole and Indan‐1,3‐dione Functionalities to Prepare an Efficient Non‐Fullerene Acceptor for Solution‐Processable Bulk‐Heterojunction Solar Cells

Abstract

As olution-processable, non-fullerene electron acceptor,2 ,2'-( ((5,5-dioctyl-5 H-dibenzo[b,d]silole-3,7-diyl)bis-(thiophene-5,2-diyl))bis(methanylylidene))bis(1 H-indene-1,3(2 H)-dione) (called N5)c omprised of dibenzosilole and 1,3-indanedione building blocks was designed, synthesized, and fully characterized. N5 is highly soluble in variousorganic solvents, has high thermals tability,a nd has energy levels matching those of archetypal donor poly(3-hexylthiophene).Solution-processable, bulk-heterojunction solar cells afforded promising power conversion efficiency of 2.76 %w hen N5 was used as an on-fullerene electron acceptor along with the conventional donorp olymer poly(3-hexylthiophene). As per our knowledge,t he material reported herein is the first example in the literature where synchronous use of such building blocks is demonstrated in the design an efficient, non-fullerene acceptor.

Bis-Silicon-Bridged Stilbene: A Core for Small-Molecule Electron Acceptor for High-Performance Organic Solar Cells

“…32 However, the photovoltaic performance of small-molecule NFAs based on silole derivatives was far from satisfactory, a DBS-based smallmolecule NFA only delivered a PCE of 2.76%. 33 Yamaguchi and co-workers reported a series of π-conjugated polymers based on BSS, which exhibit an intense blue to greenish-blue emission. 34 The easy tuning of absorption and emission scope and extended coplanar skeleton of BSS make it a valuable building block for the design of new organic π-functional materials.…”

“…Heeger and co-workers reported a small molecular DTS­(PTTh 2 ) 2 based on DTS exhibiting a high saturation hole mobility of 0.12 cm 2 V –1 s –1 and I on / I off ∼ 10 7 , and they fabricated solution-processable small-molecule solar cells with a designed small-molecule donor p -DTS­(FBTTh 2 ) 2 and achieved an encouraging PCE over 8% as well . However, the photovoltaic performance of small-molecule NFAs based on silole derivatives was far from satisfactory, a DBS-based small-molecule NFA only delivered a PCE of 2.76% . Yamaguchi and co-workers reported a series of π-conjugated polymers based on BSS, which exhibit an intense blue to greenish-blue emission .…”

Brominated Small-Molecule Acceptors with a Simple Non-fused Framework for Efficient Organic Solar Cells

“…For the reduction of synthesis cost, one way is the design and synthesis of the SMA using a simple non-fused-ring structure as a central building block. − Then, some prominent non-fused-ring acceptors with a phenyl substituent core, such as DF-PCIC, PTIC, DOC2C6-2F, and HC-PCIC, have been explored by Chen’ and Bo’ group, wherein the non-covalent interactions are employed to enhance the planarity of these molecules, leading to PCEs exceeding 11% in single-junction PSCs. − Besides the phenyl substituent, some research studies explored non-fused ring-based acceptors with cheap fluorene as the central core moiety. − Coupling a simple moiety such as thiophene onto the fluorene core provides a modular approach to design a simple A-π-D-π-A-type acceptor with a non-fused framework. Meanwhile, the fluorene core also provides a means of facilitating solubility via attachment of alkyl substituents .…”

Non‐Fullerene Small Molecule Acceptors Containing Barbituric Acid End Groups for Use in High‐performance OPVs

“…They have several advantages, including their simple synthesis, strong and broad absorption in the UV–Vis region, and easily tunable energy levels . Electron‐deficient groups, such as rhodanine (RH), 1,3‐indandione (IN), and 1,1‐dicyanomethylene‐3‐indanone (CNIN) have been widely used as acceptor units, together with fused‐ring‐based electron‐rich groups, such as carbazole (Cz), fluorene (Flu), indacenodithiophene (IDT), and indacenodithienothiophene (IDTT) …”