A waste-minimized synthetic approach to semiconducting arylacetylenes for solution processable optoelectronic devices

By merging the advantages of solar cells fabricated from small molecules/polymers donor with new eco-friendly synthetic procedures, new opportunities for the production of green energy from green materials may emerge. The synthetic methodologies nowadays available for organic semiconductors are extremely costly from both chemical and environmental point of views, and these aspects may seriously affect their large-scale application. An effective sustainable synthetic approach that focuses on reducing at the minimum the production of waste per Kg of desired material (E-factor minimization) is therefore highly desirable. In this regard, and in continuation of our efforts in understanding the interrelationships between molecular structure and BHJ performance, we report here the sustainable synthesis of a new family of soluble extended pi-conjugated arylacetylenic optoelectronic materials with a push-pull architecture. Quite importantly, green reaction media were used, organic solvents accounting for more than 80% of the waste production of a process. Further, the use of recoverable heterogeneous catalysts simplified the process purification steps, avoiding in most cases the need for chromatography. By adopting the newly defined synthetic protocols a 94.4-99.1% reduction of waste has been achieved. Solution-processable field-effect transistors and photovoltaic cells were also fabricated for all compounds, and their device response trends will be discussed