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Correlating morphology and photovoltaic device performance Enrique D. Gomez, Pennsylvania State University, DMR 1056199. The role of structure in the active layer on device performance is not fully understood
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Correlating morphology and photovoltaic device performanceEnrique D. Gomez, Pennsylvania State University, DMR 1056199 • The role of structure in the active layer on device performance is not fully understood • We studied a model system, mixtures of poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene)poly(3-hexylthiophene) (PBTTT) and phenyl-C71-butyric acid methyl ester (PCBM). • Using a simple model which assumes that only the outer region of each PBTTT domain contributes to the photocurrent, we can predict device data from the length scales of the morphology • Thus, the short-circuit current is related to the domain size (or domain spacing) through the exciton diffusion length. Exciton diffusion length Short-circuit current of PBTTT/PCBM solar cells vs. domain spacing of the active layer obtained from grazing-incidence small angle X-ray scattering1 References: 1. Kozub, Vakhshouri, Kesava, Wang, Hexemer and Gomez, Chem. Commun., 2012, 48, 5859 2. Vakhshouri, Kozub, Wang, Salleo, Gomez, PRL, 2012, 108, 026601. 3. Vakhshouri, Kesava, Kozub, Gomez, Materials Lettersin press
Introducing research to undergraduate studentsEnrique D. Gomez, Pennsylvania State University, DMR 1056199 • Working hypothesis: exposure of undergraduate students to research early in their careers will motivate them to pursue advanced degrees. • This summer I mentored six undergraduate students: 2 seniors (Nabeel Dahod and Tingting Jiang), 3 juniors (Omar Padilla, Morgan Young and Adebola Adepoju) and one sophomore (Michelle Yang) in my group who were involved in this project • PI met with the students weekly and three of the students gave a poster presentation at the end of the summer • Further efforts included a workshop on organic solar cells to 20 undergraduate students over the summer Omar Padilla and Enrique Gomez in the lab. Dr. Gomez mentored Omar the summer of 2012 on characterizing the charge mobility of polymer/fullerene mixtures.