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| Calendar: | ALS Calendar |
| Title: | ALS Special Seminar | John Tumbleston |
| When: | 01/30/2013 9:30 AM - 10:30 AM |
| Description: | ALS Special Seminar Wed, January 30, 2013 9:30 - 10:30 6-2202 Conf Room Host: Cheng Wang Presented by: John Tumbleston North Carolina State University Title: Unraveling Structure-Performance Relationships in Plastic Solar Cells at the ALS Abstract: The performance of bulk heterojunction (BHJ) polymer/fullerene solar cells has steadily improved over the last decade with power conversion efficiencies now near 10%. Progress has been made mostly through trial and error optimization of materials chemistry and device processing often without a clear link between BHJ morphology and performance. This talk will overview results from soft X-ray microscopy (BL 5.3.2.2) and scattering (BL 11.0.1.2) along with complimentary hard X-ray scattering (BL 7.3.3) that when taken together are able to unravel structure-performance relationships in BHJ solar cells. The soft X-ray scattering techniques in particular allow for domain size, domain purity, and properties of electron donor/acceptor interfaces to be quantitatively determined. In terms of materials chemistry, we show how the performance-boosting synthetic technique of fluorine substitution on the polymer backbone leads to larger and purer BHJ domains with polymer crystallites oriented more strongly face-on the substrate. Fluorine substitution also allows for control of polymer orientation with respect to donor/accepter interfaces, a new morphological property in BHJ solar cells. Also in terms of device processing, we show that solvent choice can have a significant morphological impact which in some cases can lead to drastic performance changes but in others can leave performance relatively unaffected. |
| Location: | 6-2202-CR(20) |
| Author: | areza@lbl.gov |
