Crystalline Si films incorporated with Al are important for applications in microelectronics and solar cells. In this paper, we report on the morphology of crystalline Si surfaces in Al/amorphous-Si bilayer thin films under ion beam irradiation at 100 °C. Micro-Raman and transmission electron microscopy studies show that best crystallization is achieved at a fluence of 1 × 1012 ions cm−2. The contact angle of Si surfaces (after chemically etched unreacted Al), referred to as absorber surfaces, decreases with increasing ion fluence. These surfaces are hydrophobic in nature and the hydrophobicity decreases with increasing ion fluence. Fractal and multifractal analysis of atomic force microscopy images, along with system energy/unit cell and Laplace pressure calculations, supports our observations. Moreover, the calculated multiple scattering cross sections of light, along with reflectivity measurements, indicate that absorber surfaces of best crystalline films have the lowest reflectivity. The present results suggest that such surfaces having low optical reflectance and a hydrophobic nature can be used as photon absorber layers for advanced solar cell devices.

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The field of bioelectronics leverages the optoelectronic properties of synthetic materials to interface with living systems. These applications require materials that are conductive, aqueous-processible, biocompatible, and can be chemically modified for biofunctionalization. While conjugated polymers and polyelectrolytes have been reported that demonstrate several of these features, materials that offer each of these properties simultaneously are rare. Here, we develop copolymers of anionic polyelectrolyte poly(4-(2,3-dihydrothieno [3,4-b]-[1,4]dioxin-2-yl-methoxy)-1-butanesulfonic acid, sodium salt) (PEDOT-S) containing structural units with amine-reactive N-hydroxysuccinimide (NHS)-esters. The reported PEDOT-NHS copolymers demonstrate water solubility and electrical conductivities similar to previously reported PEDOT-S, as well as the ability to bind important amine-rich biomaterials. Furthermore, the PEDOT-NHS copolymers were biocompatible and hemocompatible and therefore show promise for next-generation bioelectronic and regenerative engineering applications.

In the present study, crystallization of amorphous-Si (a-Si) in Al/a-Si bilayer thin films under thermal annealing and ion irradiation has been investigated for future solar energy materials applications.

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