One potential solution to the world’s expanding energy needs is the harnessing of solar energy—an inexhaustible energy source. In part because of the relatively low efficiency, high cost, and short durability of solar cells, only 2% of energy in the US presently comes from solar.[1] Thin film polymer solar cells offer the potential of making solar energy more affordable.[2- 5] However, one of the challenges of polymer solar cells is the limited absorption range. Certain conditions lead to a red shift in absorption offering the possibility of increased light absorption, but the effect is not fully understood. In order to understand what causes a red shift we must study morphology. The morphology of polymer chains refers to their form and structure. Two aspects of morphology are chain conformation and aggregation. Chain conformation refers to the structural arrangement of the chains and aggregation refers to direct mutual attraction of the molecules. The morphology of polymer chains in solution depends on the solvent used and the polymer concentration [6,7] and has a great influence on the conjugation lengths of the chains which in turn has a great influence on absorption. [6,8] Longer conjugation lengths cause the absorption spectrum to red shift. [6,7,9,10] Because of these effects, understanding solvent effects on absorption could make polymer solar cells more efficient. A popular polymer used in solar cells is MEH-PPV [Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4- phenylenevinylene and in particular, the morphology of MEH-PPV chains in solution has a great influence on absorption [6,7,11]. This study will investigate the absorption spectrum of MEH-PPV in solution both experimentally and theoretically.

Date Published: 21 December 2016
PDF: 9 pages
Proc. SPIE 10174, International Symposium on Clusters and Nanomaterials, 101740J (21 December 2016); doi: 10.1117/12.2235800

Published in SPIE Proceedings Vol. 10174:
International Symposium on Clusters and Nanomaterials
Puru Jena; Anil K. Kandalam, Editor(s)