Angelika Basch

Combined plasmonic and dielectric rear reflectors for enhanced photocurrent in solar cells

To reduce the use of fossil fuels and to fulfill the increasing energy demand for the fast growing population of our planet, renewable energies need to be more efficient and cheaper. A way of reducing the silicon solar cell cost for today’s technology is by using thinner layers and therefore less of the silicon material that accounts for about 50% of the photovoltaic module cost. However, due to weak absorption of infrared light in crystalline Si (c-Si), a significant fraction of solar energy is not converted into electricity in thin-film devices. Proper light management can potentially lead to ultra-efficient thin solar cells. 1 One method of achieving absorption enhancement in thin-film solar cells is through the excitation of localized surface plasmons in metal nanoparticles. These can be used as subwavelength scattering elements to couple a large fraction of incident light into trapped modes within a nearby semiconductor layer. 2‐10

Enhanced light trapping in solar cells using snow globe coating

A novel method, snow globe coating, is found to show significant enhancement of the short circuit current JSC (35%) when applied as a scattering back reflector for polycrystalline silicon thin-film solar cells. The coating is formed from high refractive index titania particles without containing binder and gives close to 100% reflectance for wavelengths above 400 nm. Snow globe coating is a physicochemical coating method executable in pH neutral media. The mild conditions of this process make this method applicable to many different types of solar cells. Copyright

Triaqua(oxalato-O, O')oxovanadium(IV) dihydrate

In the structure of the title compound, [VO(C(2)O(4))(H(2)O)(3)]. 2H(2)O, the V atom of the oxovanadium(IV) cation is coordinated to one bidentate oxalate anion and three water molecules, resulting in a neutral complex. Two more water molecules are not coordinated to the V atoms but are involved in the hydrogen-bonding network, which consists of ten different hydrogen bonds.

Highly Reflective Dielectric Back Reflector for Improved Efficiency of Tandem Thin-Film Solar Cells

We report on the prototyping and development of a highly reflective dielectric back reflector for application in thin-film solar cells. The back reflector is fabricated by Snow Globe Coating (SGC), an innovative, simple, and cheap process to deposit a uniform layer of TiO2 particles which shows remarkably high reflectance over a broad spectrum (average reflectance of 99% from 500u2009nm to 1100u2009nm). We apply the highly reflective back reflector to tandem thin-film silicon solar cells and compare its performance with conventional ZnO:Al/Ag reflector. By using SGC back reflector, an enhancement of 0.5u2009mA/cm2 in external quantum efficiency of the bottom solar cell and an absolute value of 0.2% enhancement in overall power conversion efficiency are achieved. We also show that the increase in power conversion efficiency is due to the reduction of parasitic absorption at the back contact; that is, the use of the dielectric reflector avoids plasmonic losses at the reference ZnO:Al/Ag back reflector. The Snow Globe Coating process is compatible with other types of solar cells such as crystalline silicon, III–V, and organic photovoltaics. Due to its cost effectiveness, stability, and excellent reflectivity above a wavelength of 400u2009nm, it has high potential to be applied in industry.

Texture Effects in the Delithiation of Lithium Cobalt Oxide

The effects of aqueous delithiation of lithium cobalt oxide crystals on the crystal texture and etching patterns has been studied by electron microscopy, x-ray and neutron diffraction at high resolution. The delithiation proceeds to exfoliation and in the process textural patterns that appear have been associated with periodic strains in the crystals developed by the delithiation.