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R. G. Herb Condensed Matter Seminar
Improved Charge Collection in Nanostructured Organic Semiconductor Solar Cells
Date: Thursday, April 28th
Time: 10:00 am
Place: 5310 Chamberlin
Speaker: Charles Black, Brookhaven National Lab
Abstract: High-performance organic semiconductor solar cell active layers form via a self-assembly process of phase separation of blended donor and acceptor materials. Achieving optimal device performance requires a delicate balance of trapping the blended material in a non-equilibrium configuration. I will describe our experimental efforts to confine both organic semiconductors and semiconductor blends within nanometer-scale volumes to better control material phase separation and understand the effect of geometry on the material structure, its electronic properties, and its photovoltaic performance.

As one example, confining blended poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methyl ester organic solar cell active layers within nanometer-scale cylindrical volumes more than doubles the supported photocurrent density compared to equivalent unconfined volumes of the same blend, and increases the poly(3-hexylthiophene) hole mobility in the blend by more than 500 times. Grazing incidence x-ray diffraction measurements show that the confining volume disrupts polymer ordering by reducing crystallinity and grain size, as well as changing crystal orientation.
Host: Mark Eriksson
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