Search for: All records

Abstract Design strategies to achieve degradation and ideally closed‐loop recycling of organic semiconductors have attracted great interest in order to minimize the electronic waste (E‐waste). In this work, three ester‐incorporated monomers were synthesized by the names of Thiophene‐Ester‐Ethylene‐Thiophene (TEET), Thiophene‐Ester‐Methylene‐Thiophene (TEMT), and Thiophene‐Ester‐Thiophene (TET), which were co‐polymerized via Stille polycondensation with a benzodithiophene (BnDT) π‐conjugated unit to yield a series of ester‐incorporated polymers: PBnDT‐TEET, PBnDT‐TEMT, and PBnDT‐TET. While the ester‐only linker can maintain some extended conjugation in PBnDT‐TET, the other two ester linkers having conjugation breaking units result in isolated conjugated segments in PBnDT‐TEET and PBnDT‐TEMT, evidenced by UV‐Vis and CV results. This yields an improved photovoltaic performance of PBnDT‐TET compared to PBnDT‐TEET. While all three polymers can depolymerize under methanolysis, the alternating co‐polymer PBnDT‐TEET demonstrates the highest recyclability potential with a single dimethyl ester‐functionalized product with an excellent 92 % isolated yield, which can then be repolymerized to reobtain PBnDT‐TEET with a 36 % yield. This work provides a framework towards achieving recyclable organic semiconductors to reduce E‐waste. Although the incorporation of ester linkers allowed for closed‐loop recycling, the low solar cell efficiency of PBnDT‐TEET highlights the significant challenge in achieving both recycling and high device performance. 

Abstract Conjugated polymers have a long history of exploration and use in organic solar cells, and over the last twenty‐five years, marked increases in the solar cell efficiency have been achieved. However, the synthetic complexity of these materials has also drastically increased, which makes the scalability of the highest‐efficiency materials difficult. If conjugated polymers could be designed to exhibit both high efficiency and straightforward synthesis, the road to commercial reality would be more achievable. For that reason, a new synthetic approach was designed towards PTQ10 (=poly[(thiophene)‐alt‐(6,7‐difluoro‐2‐(2‐hexyldecyloxy)quinoxaline)]). The new synthetic approach to make PTQ10 brought a significant reduction in cost (1/7th the original) and could also easily accommodate different side chains to move towards green processing solvents. Furthermore, high‐efficiency organic solar cells were demonstrated with a PTQ10:Y6 blend exhibiting approximately 15 % efficiency.