title: Novel back-reflector architecture with nanoparticle based buried light-scattering microstructures for improved solar cell performance.
abstract: A new back-reflector architecture for light-management in thin-film solar cells is proposed that includes a morphologically smooth top surface with light-scattering microstructures buried within. The microstructures are pyramid shaped, fabricated on a planar reflector using TiO2 nanoparticles and subsequently covered with a layer of Si nanoparticles to obtain a flattened top surface, thus enabling growth of good quality thin-film solar cells. The optical properties of this back-reflector show high broadband haze parameter and wide angular distribution of diffuse light-scattering. The n-i-p amorphous silicon thin-film solar cells grown on such a back-reflector show enhanced light absorption resulting in improved external quantum efficiency. The benefit of the light trapping in those solar cells is evidenced by the gains in short-circuit current density and efficiency up to 15.6% and 19.3% respectively, compared to the reference flat solar cells. This improvement in the current generation in the solar cells grown on the flat-topped (buried pyramid) back-reflector is observed even when the irradiation takes place at large oblique angles of incidence. Finite-difference-time-domain simulation results of optical absorption and ideal short-circuit current density values agree well with the experimental findings. The proposed approach uses a low cost and simple fabrication technique and allows effective light manipulation by utilizing the optical properties of micro-scale structures and nanoscale constituent particles.
authors.affiliation: Department of Physics and I3N, University of Aveiro, Campus Universitário de Santiago 3810-193, Aveiro, Portugal.
authors.forename: Derese
authors.initials: D
authors.lastname: Desta
authors.affiliation: Department of Physics and Astronomy-iNANO, Aarhus University, Gustav Wieds Vej 14, DK-8000, Aarhus, Denmark. sanjayk.ram@gmail.com.
authors.forename: Sanjay K
authors.initials: SK
authors.lastname: Ram
authors.affiliation: IMM-Consiglio Nationale delle Ricerche, via Gobetti 101, 40129, Bologna, Italy.
authors.forename: Rita
authors.initials: R
authors.lastname: Rizzoli
authors.affiliation: IMM-Consiglio Nationale delle Ricerche, via Gobetti 101, 40129, Bologna, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Bellettato
authors.affiliation: IMM-Consiglio Nationale delle Ricerche, via Gobetti 101, 40129, Bologna, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Summonte
authors.affiliation: Department of Physics and Astronomy-iNANO, Aarhus University, Gustav Wieds Vej 14, DK-8000, Aarhus, Denmark. sanjayk.ram@gmail.com.
authors.forename: Bjarke R
authors.initials: BR
authors.lastname: Jeppesen
authors.affiliation: Department of Physics and Astronomy-iNANO, Aarhus University, Gustav Wieds Vej 14, DK-8000, Aarhus, Denmark. sanjayk.ram@gmail.com.
authors.forename: Pia B
authors.initials: PB
authors.lastname: Jensen
authors.affiliation: Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4A, DK-9220 Aalborg East, Denmark.
authors.forename: Yao-Chung
authors.initials: YC
authors.lastname: Tsao
authors.affiliation: Institut für Verbrennung und Gasdynamik, Universität Duisburg-Essen, Lotharstr 1, 47048 Duisburg, Germany.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Wiggers
authors.affiliation: Department of Physics and I3N, University of Aveiro, Campus Universitário de Santiago 3810-193, Aveiro, Portugal and Walter Schottky Institute and Physik Department, Technische Universität München, Am Coulombwall 4, 85748 Garching, Germany.
authors.forename: Rui N
authors.initials: RN
authors.lastname: Pereira
authors.affiliation: Department of Physics and Astronomy-iNANO, Aarhus University, Gustav Wieds Vej 14, DK-8000, Aarhus, Denmark. sanjayk.ram@gmail.com.
authors.forename: Peter
authors.initials: P
authors.lastname: Balling
authors.affiliation: Department of Physics and Astronomy-iNANO, Aarhus University, Gustav Wieds Vej 14, DK-8000, Aarhus, Denmark. sanjayk.ram@gmail.com.
authors.forename: Arne Nylandsted
authors.initials: AN
authors.lastname: Larsen