Multifunctional Heteropentalenes: From Synthesis to Optoelectronic Applications

Abstract

In the broad family of heteropentalenes, the combination of two five-membered heterocyclic rings fused in the [3,2- b ] mode has attracted the most significant attention. The relatively straightforward access to these structures, being a consequence of the advances in the last two decades, combined with their physicochemical properties which match the requirements associated with many applications has led to an explosion of applied research. In this Perspective, we will discuss the recent progress of heteropentalenes’ usefulness as an active element of organic light-emitting diodes and organic field-effect transistors. Among the myriad of possible combinations for the different heteroatoms, thieno[3,2- b ]thiophenes and 1,4-dihydropyrrolo[3,2- b ]pyrroles are subject to the most intense studies. Together they comprise a potent optoelectronics tool resulting from the combination of appreciable photophysical properties, chemical reactivity, and straightforward synthesis.

Thiazolo[5,4-d]thiazoles with a spirobifluorene moiety as novel D–π–A type organic hosts: design, synthesis, structure–property relationship and applications in electroluminescent devices

“…The advantage of the hybrid electron-rich character of thiophene together with its planar structure benefits the p-conjugation extension. 59 Generally, thiophene-based materials are among the most widely applied as parts of organic semiconductors (OSCs). [60][61][62][63] Among aromatic compounds, fluorene derivatives, in particular the 9,9 0 -spirobifluorene (SBF) segment, have been effectively employed to adjust solubility.…”

Chalcogenopheno[3,2-b]pyrrole-Containing Donor–Acceptor–Donor Organic Semiconducting Small Molecules for Organic Field-Effect Transistors

“…Heteropentalenes are an important family of heterocyclic compounds frequently used as building blocks for organic semiconducting materials (OSMs) . Among the heteropentalenes, thieno­[3,2- b ]­thiophene is the “star” molecule, which is employed as a donor unit in organic semiconducting polymers, such as PDPP-TT (poly­[2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole- alt -5,5-(2,5-di­(thien-2-yl)­thieno [3,2 -b ]-thiophene)]), which has been used in organic field-effect transistors (OFETs), − and polycyclic ring systems, such as ITIC (3,9-bis­(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis­(4-hexylphenyl)-dithieno­[2,3- d :2,3′- d′ ]- s -indaceno­[1,2- b :5,6- b′ ]­dithiophene) derivatives − and Y-series non-fullerene small molecular acceptors used in organic photovoltaics (OPVs). − In recent decades, there has been significant interest in organic electronics, including but not limited to OFETs, OPVs, and organic light-emitting diodes (OLEDs). − Of particular importance in this area of research is the reduction of the band gap of organic semiconductors, which enhances both charge-transfer and optical absorption characteristics.…”

Thiazole fused S,N-heteroacene step-ladder polymeric semiconductors for organic transistors

“…22 Another interesting class of fused ladder-type building blocks with promising electronic and optical properties are based on heteroacenes. [23][24][25][26][27][28][29][30][31][32][33][34] Among the various reported building blocks, S,N-heteroacenes consisting of fused thiophene and pyrrole rings, a structural analogue of the electrondonating dithieno[3,2-b:2 0 ,3 0 -d]pyrrole (DTP), unit are of particular interest. [35][36][37][38] Introducing solubilizing substituents on the sp 2 -hybridized nitrogen atom of the pyrrole moiety, enhancing the intramolecular charge transfer (ICT) interactions, and tuning the energy levels are promising strategies for inuencing the properties required to achieve high performance organic thin-lm transistors (OTFTs).…”