Materials Science

Silicon Goes Organic

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Science  15 Apr 2011:
Vol. 332, Issue 6027, pp. 285
DOI: 10.1126/science.332.6027.285-a

Though organic- (i.e., predominantly carbon-) based solar cells are less efficient than their inorganic counterparts, they have the advantage of being processed from solutions and thus can be fashioned at large scale on curved or flexible substrates. Graham et al. explored the use of polydimethylsiloxane (PDMS) as a solvent additive for improving organic solar cell performance without the need for subsequent thermal or solvent annealing steps. Low concentrations of PDMS were added in the fabrication of cells, with thiophene and isoindigo-containing oligomers as the electron donor and PC61BM as the acceptor. There was significant variation in the efficiencies of the cells obtained in each of the three labs where the experiments were performed, but in all cases the addition of PDMS improved the cell performance and decreased the variability between cells fabricated within a single lab. The PDMS strongly altered the film morphology, with a decrease in roughness and feature size (as shown left to right above), and reduced the need for postfabrication thermal annealing. Because plastic syringes are commonly used for fabricating organic solar cells, the variability in reported efficiencies may be partly due to syringe-derived PDMS contamination.

ACS Appl. Mater. Interfaces 3, 10.1021/am2000328 (2011).

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