Céline Pahud | EPFL Graph Search

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Stencil-Nanopatterned Back Reflectors for Thin-Film Amorphous Silicon n-i-p Solar Cells

Jürgen Brugger, Christophe Ballif, Franz-Josef Haug, Andreea Veronica Savu, Oscar Vazquez Mena, Mona Julia Katharina Klein, Céline Pahud

We fabricated amorphous silicon n-i-p solar cells with two types of nanopatterned back reflectors using stencil lithography. One reflector type has a plasmonic grating that is embedded in the ZnO layer; the other one has a metallic grating patterned on top of the Ag layer. From comparing the short-circuit current densities of the two device types, we conclude that light trapping through grating coupling is more efficient than coupling of light through the excitation of localized surface plasmons. The back reflectors were patterned with dot arrays by evaporation of Ag through millimeter-size stencil membranes. The stencils themselves were patterned by wafer-scale nanosphere lithography. The dot arrays have a periodicity of 428 nm and efficiently scatter light in the near-infrared wavelength range. Both back reflectors types lead to the same morphology for the silicon films. This allows us a fair comparison of the two light coupling mechanisms. We found a 14% and 19% short-circuit current density enhancement for the plasmonic and for the metallic grating, respectively. The external quantum efficiency gains between 550 and 650 nm show similar guided modes resonances for both device types, but the excitation is stronger for the device with the metallic grating.

Ieee-Inst Electrical Electronics Engineers Inc2013

Light-trapping in the near field: the case for plasmonic thin-film solar cells

Christophe Ballif, Hans Peter Herzig, Franz-Josef Haug, Toralf Scharf, Karin Söderström, Ali Naqavi, Céline Pahud

We study the plasmonic and the non-plasmonic regimes of operation of a thin-film amorphous-silicon solar cell. By rigorous calculation, we discuss the impact of the cell geometry on the nature of its optical resonances.

2013

New progress in the fabrication of n–i–p micromorph solar cells for opaque substrates

Christophe Ballif, Franz-Josef Haug, Matthieu Despeisse, Mathieu Gérard Boccard, Sylvain Nicolay, Grégory Bugnon, Laura Ding, Karin Söderström, Gaetano Parascandolo, Martial Duchamp, Simon Hänni, Céline Pahud, Rémi Biron

In thispaper,weinvestigatetandemamorphous/microcrystallinesiliconsolarcellswithasymmetric intermediatereflectorsgrowninthen–i–psubstrateconfiguration.Wecomparedifferenttypesof substrateswithrespecttotheirlight-trappingpropertiesaswellastheirinfluenceonthegrowthof single-junctionmicrocrystallinecells.Ourmostpromisingbackreflectorcombinesatexturedzinc oxide filmgrownbylow-pressurechemicalvapordeposition,asilverfilmforreflection,andazinc oxide bufferlayer.Grownonthissubstrate,microcrystallinecellsexhibitexcellentresponseinthe infrared whilekeepinghighopen-circuitvoltageandfillfactor,leadingtoefficienciesofupto10.0%. After optimizingthemorphologyoftheasymmetricintermediatereflector,weachieveann–i–p micromorphsolarcellstabilizedefficiencyof11.6%,using270nmand1.7 mm ofsiliconfortheabsorber layer oftheamorphoustopcellandthemicrocrystallinebottomcell,respectively.Usingthisoriginal devicearchitecture,wereachefficienciesclosetothoseofstate-of-the-artn–i–pandp–i–nmicro- morph devices,demonstratingapromisingroutetodeposithigh-efficiencythin-filmsiliconsolarcells on opaquesubstrates.

Elsevier2013