ABSTRACT:The optical transparency, thermal resistance, intermolecular interaction, and mechanical properties of poly(styrene-block-butadiene-block-styrene) (SBS), which were modified by blending with crystalline polypropylene (PP) or amorphous polystyrene (PS), were analyzed. The dynamic mechanical test indicated that the PP exhibited an intermolecular interaction with SBS and PS was compatible with SBS. The optical properties indicated that the direction of the light was changed due to the difference between the refractive indices of SBS and the added modifiers. Additionally, refraction and reflection occurred at the interface, reducing the transparency of SBS. The thermal resistance of SBS clearly improved upon modification by the addition of crystalline PP polymer. The thermal treatment increased the tensile strength and the elongation at breakage of modified SBS by reducing the internal stress, which was generated during the blending process.
This study reports the use of cross-shaped pattern epitaxial lift-off (ELO) technology to release crack-free single crystal epilayers with a solar cell structure from a gallium arsenide (GaAs) substrate. A cross-shaped pattern array was used to define cell size and provide the etch path for the etchant solution. AlAs was used as a sacrificial layer and etched using a hydrofluoric acid etchant through the cross-shaped hole. Results indicate that the entire wafer can be etched simultaneously. The desired carrier, i.e., the electroplate nickel substrate, can directly contact the epilayer without wax or low-viscosity epoxy, and can also be applied to an external force through magnetic attraction to decrease the release time. After the cross-shaped pattern ELO process, the separated GaAs substrate can be recycled through chemical cleaning. The performance of solar cells grown on new and recycled GaAs substrates remained above 90% of the initial performance when the substrate was recycled less than three times
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