Seeking preparation of high-performance donor–acceptor (D–A) polymers based on bare thiophene units in a more environmentally friendly and faster way, we have carried out a direct arylation polymerization (DAP) of two starting β-unprotected thiophene-containing monomers (indaceno­dithiophene (IDT) and thiophene–quinoxaline–thiophene (TQ)). Through modulating DAP time and heating method, the resulting IDT–TQ polymer shows a relatively well-defined structure with low content of structural defects, as demonstrated by high temperature 1H NMR, MALDI-TOF-MS, and elemental analysis. Integrating this polymer into bulk-heterojunction solar cells with PC71BM can induce an enhanced OPV performance compared to the other structural analogues that retain a certain amount of unwanted structural defects. However, the film morphology and crystallinity are negligibly influenced by the degree of the structural defects. Through a combination of detailed electrical measurements using light intensity dependence and net photocurrent, we are able to correlate the different photovoltaic performances in structure–function relationships with the extent of the structural defects. Our study indicates that DAP is a promising asset for environmental production of many valuable thiophene-containing polymers for electroactive and photoactive applications.

To understand the effects rendered on the relevant basic physical properties and device function by controlling the regiochemistry of the cyclopenta[1,2-b:5,4-b']dithiophene-fluorobenzo[c][1,2,5]thiadiazole polymer (hereafter referred to as the CDT-FBT polymer), two polymers, the regiorandom polymer (RA) and regioregular version (RR), respectively, are synthesized and characterized. In addition, an efficient route for synthesizing a key monomer for RR using various synthesis scope and optimizing the reaction conditions is discussed. Although RA exhibits optical, electrochemical, and morphological properties similar to RR, it shows better field-effect transistor (FET) performance. Surprisingly, by employing a capillarity-mediated sandwich-casting process on a nanogrooved substrate, an unprecedented mobility of 17.8 cm V s is obtained for RA-based FETs; this mobility value is almost twofold greater than those of the corresponding RR-based FETs. For the first time, this study challenges previously reported results in that high carrier mobility is related to the high degree of polymer order induced by the backbone regioregularity.

The enhanced SMA order ranges in well-intermixed 3-D textures enabled an ultrafast Channel II process, affording a highest efficiency of 12.01%.

The novel constitutional isomeric acceptors (o-F-ITIC and m-F-ITIC) are developed and they show the huge disparity of intermolecular interactions and/or arrangements with the donor polymer leading a significant variation in PCE of OSCs.