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Full-Text Articles in Nanoscience and Nanotechnology

The Impact Of Controlled Solvent Exposure On The Morphology, Structure And Function Of Bulk Heterojunction Solar Cells, Raghavendra R. Hegde Dr Dec 2012

The Impact Of Controlled Solvent Exposure On The Morphology, Structure And Function Of Bulk Heterojunction Solar Cells, Raghavendra R. Hegde Dr

Raghavendra R Hegde Dr

Films of poly(3-hexyl thiophene) (P3HT):[6,6]-phenyl C61-butyric acid methyl ester (PCBM) were controllably exposed to CS2 vapor in a column with a linear solvent vapor pressure gradient. Changes in the morphology of the P3HT:PCBM thin film were monitored and correlated to the ability of this thin film to act as the active layer in an organic solar cell. The results show that the crystallinity and crystal size of the P3HT increase initially with solvent vapor pressure and annealing time, but longer exposure to solvent decreases P3HT crystallinity and photovoltaic efficiency. Neutron reflectivity indicates that the PCBM segregates to the Si substrate …


The Miscibility And Depth Profile Of Pcbm In P3ht: Thermodynamic Information To Improve Organic Photovoltaics, Raghavendra R. Hegde Dr Apr 2012

The Miscibility And Depth Profile Of Pcbm In P3ht: Thermodynamic Information To Improve Organic Photovoltaics, Raghavendra R. Hegde Dr

Raghavendra R Hegde Dr

Recent work has shown that poly(3-hexylthiophene) (P3HT) and the surface-functionalized fullerene 1-(3-methyloxycarbonyl)propyl(1-phenyl[6,6])C(61) (PCBM) are much more miscible than originally thought, and the evidence of this miscibility requires a return to understanding the optimal morphology and structure of organic photovoltaic active layers. This manuscript describes the results of experiments that were designed to provide quantitative thermodynamic information on the miscibility, interdiffusion, and depth profile of P3HT : PCBM thin films that are formed by thermally annealing initial bilayers. It is found that the resultant thin films consist of a 'bulk' layer that is not influenced by the air or substrate surface. …