Sputtered aluminum oxide and p+ amorphous silicon back-contact for improved hole extraction in polycrystalline CdSexTe1-x and CdTe photovoltaics

A thin layer of Al2O3 at the back of CdSexTe1-x/CdTe devices is shown to passivate the back interface and drastically improve surface recombination lifetimes and photoluminescent response. Despite this, such devices do not show an improvement in open-circuit voltage (VOC.) Adding a p + amorphous silicon layer behind the Al2O3 bends the conduction band upward, reducing the barrier to hole extraction and improving collection. Further optimization of the Al2O3, amorphous silicon (a-Si), and indiumdoped tin oxide (ITO) layers, as well as their interaction with the CdCl2 passivation process, are necessary to translate these electrooptical improvements into gains in voltag

Final optimized geometry structure of oxygen atom adsorbed on the graphite with carbonyl functional groups.

<p>Final optimized geometry structure of oxygen atom adsorbed on the graphite with carbonyl functional groups.</p

Final optimized geometry structure of single oxygen atom adsorbed on the graphite with quinone functional groups.

<p>Final optimized geometry structure of single oxygen atom adsorbed on the graphite with quinone functional groups.</p

Sumarize of the main parameters of geometry structure and adsorption energy.

<p>Sumarize of the main parameters of geometry structure and adsorption energy.</p

Final optimized geometry structure of single oxygen atom adsorbed on the graphite surface with carboxyl functional groups.

<p>Final optimized geometry structure of single oxygen atom adsorbed on the graphite surface with carboxyl functional groups.</p

Optimized geometry structure of oxygen molecule adsorbed on the graphite withdifferent oxygen-containing functional groups.

<p>(Carbon atoms shown in middle gray, oxygen atoms shown in red and H atoms shown in light gray).</p

The main parameters of geometry structure and adsorption energy.

<p>The main parameters of geometry structure and adsorption energy.</p

Mulliken atomic charges.

<p>Mulliken atomic charges.</p

Final configuration of single oxygen atom adsorbed on the surface of graphite.

<p>Final configuration of single oxygen atom adsorbed on the surface of graphite.</p

Graphite cluster model.

<p>(Carbon atoms shown in middle gray, and H atoms shown in light gray).</p