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Volume 95, Issue 5, 03 August 2009
We report on a configuration to generate surface acoustic waves(SAWs) in acoustic superlattices based on -cut periodically poled lithium niobate. The coplanar electrode configuration allows inducing Rayleigh type SAWs with the elastic energy mainly concentrated in between the electrodes gap and under the crystal surface. With respect to standard interdigitated transducers using the same crystal orientation, the efficiency of the SAW generation in the proposed designs are similar, while, for the same grating period, the resonance frequency that can be achieved is two times larger.
- BIOPHYSICS AND BIO-INSPIRED SYSTEMS
95(2009); http://dx.doi.org/10.1063/1.3202393View Description Hide Description
A quinoxaline-based -conjugated donor polymer, poly[2,7-(9,9-dioctylfluorene)-alt-5,5-(-di-2-thienyl--diphenylquinoxaline)] (N-P7), was synthesized to achieve a high power conversion efficiency (PCE) of bulk heterojunction (BHJ)-based solar cells. The optical band-gap and highest occupied molecular orbital level of N-P7 were 1.95 and −5.37 eV, respectively. BHJ-based solar cells using N-P7 as a donor and phenyl butyric acid methyl ester as an acceptor gave a PCE as high as 5.5% under AM 1.5G illumination. We also investigated the effects of substituent groups of quinoxaline-based polymers on the morphology of the BHJ layer.