title: Enhanced light trapping in thin-film solar cells by a directionally selective filter.
abstract: A directionally selective multilayer filter is applied to a hydrogenated amorphous silicon solar cell to improve the light trapping. The filter prevents non-absorbed long-wavelength photons from leaving the cell under oblique angles leading to an enhancement of the total optical path length for weakly absorbed light within the device by a factor of kappa(r) = 3.5. Parasitic absorption in the contact layers limits the effective path length improvement for the photovoltaic quantum efficiency to a factor of kappa(EQE) = 1.5. The total short-circuit current density increases by DeltaJ(sc) = 0.2 mAcm(-2) due to the directional selectivity of the Bragg-like filter.
authors.affiliation: IEF5-Photovoltaik, Forschungszentrum Jülich, 52425 Jülich, Germany. c.ulbrich@fz-juelich.de
authors.forename: Carolin
authors.initials: C
authors.lastname: Ulbrich
authors.forename: Marius
authors.initials: M
authors.lastname: Peters
authors.forename: Benedikt
authors.initials: B
authors.lastname: Bläsi
authors.forename: Thomas
authors.initials: T
authors.lastname: Kirchartz
authors.forename: Andreas
authors.initials: A
authors.lastname: Gerber
authors.forename: Uwe
authors.initials: U
authors.lastname: Rau