Date

2021-9

Author

Kardelen, Deniz

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Solar energy became the leading renewable energy source due to its zero-emission profile, economic advantages and abundance of its main energy source, the sun. For conversion of solar energy to electrical energy, photovoltaics is the main approach in both academia and industry while concentrated solar thermal methods gaining significant traction in the recent years. In the field of photovoltaics, organic photovoltaics have been showing significant progress over the last two decades. Although fullerene-based molecules such as PCBM as an electron acceptor entity give satisfactory outcomes for organic solar cells, significant issues, mainly the extreme cost, prevented additional developments in the area. At this point, non- fullerene acceptors came to the scene to circumvent the issues related to fullerene- based acceptors. There are a number of novel non-fullerene acceptors in the the literature and rhodanine flanked molecules grabbed attention thanks to high power conversion effeciencies attained with the devices implement these acceptors. Currently, 19.50% PCE is reported and certified by the National Institute of Metrology for the small molecule NFA containing tandem solar cells. To push the limits even further, this study aims to synthesize logically designed novel rhodanine flanked small molecules. Target small molecules contain three main parts namely, central, bridge and terminal units. For the central unit, indacenodithiophene (IDT) core and its alkylated and stannylated derivatives were synthesized successfully. Additionally, commercial benzodithiophene (BDT) and fluorene cores were utilized for practical and comparison purposes. Aldehyde modified benzothiadiazole and di- fluorinated benzothiadiazole were synthesized as the bridging units. A novel synthetic approach for the fluorinated derivative was demonstrated for the first time in the literature. To combine bridge units and core units, Stille and Suzuki Cross- Coupling reactions were applied. For the synthesis of the terminal unit, rhodanine was ethylated successfully. The synthesis of a rhodanine with pendant amine groups were envisioned however the attempts for their synthesis were not fruitful. The synthesis of the target final products was attempted via Knoevenagel Condensation however the expected products could not be isolated. Studies towards purification of the final products and utilization of these in organic solar cells are still ongoing.

Subject Keywords

Organic solar cell, Non-Fullerene acceptor, Benzothiadiazole, Indacenodithiophene, Benzodithiophene

URI

https://hdl.handle.net/11511/93237

Collections

Graduate School of Natural and Applied Sciences, Thesis