Subcategory: Materials Science
Kheng Rowen Lapastora - University of Washington
Co-Author(s): Yilin Li and Christine Luscombe, University of Washington, Seattle, WA
Organic electronic devices such as solar cells, light-emitting diodes and transistors are one of the research hotspot in current science and technology development. They are believed to exhibit low-cost advantages over the conventional devices that use inorganic materials. It is well-known that charge carrier transport is playing an important role in these device. A high charge carrier mobility is desirable for increasing the power conversion efficiency of solar cells. The primary materials in organic electronics that are responsible for generating and transporting charge carriers are conjugated polymers. It has been revealed that charge transport is a multi-scale process that could happen locally in polymer microstructure and distantly between two polymer macrostructures. Such complexity brings significant hurdles to develop rational design rules linking the molecular structure of the conjugated polymer to its carrier mobility. In this report, we design and synthesize three D-A polymers with 3-hexylthiophene (3HT) group serving as donor and thienopyrroledione (TPD) group as acceptor. Such design excludes the effects of torsional angle on carrier mobility because the interaction between the S on 3HT group and the O on TPD group ensures the planarity between the two groups. The changing of the donor content increases the D-A interaction from polymer P3HTTPD to polymer PT3HTTPD, and therefore it is believed that an increase in carrier mobility will be observed. A synthetic route was designed and a series of experiments was conducted towards to the preparation of three conjugated polymers with different number of 3-hexylthiophene (3HT) group for organic electronics. Attempts were made to synthesize the first polymer – P3HTTPD6, which consists of a C6 alkyl chain on the thienopyrroledione (TPD) group. However, due to poor solubility of P3HTTPD6, the original route was not continued and the other two polymers were not synthesized. C12 alkyl chain was selected as an alternative for a polymer (P3HTTPD12) with potential better solubility. Since P3HTTPD12 has similar structures with P3HTTPD6, it was synthesized via the hydrolysis of a C6 intermediate (Br-3HT-TPD-C6). Experimental results showed that P3HTTPD12 exhibits good solubility in general chlorinated organic solvents (e.g. chloroform, chlorobenzene and etc.) and its molecular weight is Mw = 84 kDa (PDI = 2.0), which is a promising candidate for organic electronics. Future works include the synthesis of the other two polymers (PB3HTTPD12 and PT3HTTPD12) and the study on the properties of the three polymers for organic electronics as well as the device performance.
References: S. R. Forrest, Nature 2004, 428, 911. H. E. Katz, J. Huang, Annu. Rev. Mater. Res. 2009, 39, 71. A. Facchetti, Chem. Mater. 2011, 23, 733. R. S. Kularatne, H. D. Magurudeniya, P. Sista, M. C. Biewer, M. C. Stefen, J. Polym. Sci. A Polym. Chem. 2013, 51, 743.
Funder Acknowledgement(s): Clean Energy Institute, Anne Dinning, Michael Wolf
Faculty Advisor: Yilin Li, email@example.com
Role: When I entered my lab, my mentor had a project ready for me. He showed me the procedure for the lab and my job was to repeat the procedure. The procedure of the research is a series of chemical reaction, but it is doing the same steps over and over such as extraction, purification, filtration, and confirmation. During the confirmation of our compounds, my mentor did all the processes like using the NMR and GPC. He explained everything in detail as he was doing the processes. After confirmation, I interpreted the data and moved to the next step.