1 Scientific RepoRts | 6:22481 | DOI: 10.1038/srep22481 www.nature.com/scientificreports Experimental quantifcation of useful and parasitic absorption of light in plasmon-enhanced thin silicon flms for solar cells application seweryn Morawiec 1,2 , Jakub Holovský 3 , Manuel J. Mendes 1,4 , Martin Müller 3 , Kristina Ganzerová 3 , Aliaksei Vetushka 3 , Martin Ledinský 3 , Francesco Priolo 1,2,5 , Antonin Fejfar 3 & Isodiana Crupi 1,6 A combination of photocurrent and photothermal spectroscopic techniques is applied to experimentally quantify the useful and parasitic absorption of light in thin hydrogenated microcrystalline silicon (μc- Si:H) flms incorporating optimized metal nanoparticle arrays, located at the rear surface, for improved light trapping via resonant plasmonic scattering. The photothermal technique accounts for the total absorptance and the photocurrent signal accounts only for the photons absorbed in the μc-Si:H layer (useful absorptance); therefore, the method allows for independent quantifcation of the useful and parasitic absorptance of the plasmonic (or any other) light trapping structure. We demonstrate that with a 0.9 μm thick absorber layer the optical losses related to the plasmonic light trapping in the whole structure are insignifcant below 730 nm, above which they increase rapidly with increasing illumination wavelength. An average useful absorption of 43% and an average parasitic absorption of 19% over 400–1100 nm wavelength range is measured for μc-Si:H flms deposited on optimized self-assembled Ag nanoparticles coupled with a fat mirror (plasmonic back refector). For this sample, we demonstrate a signifcant broadband enhancement of the useful absorption resulting in the achievement of 91% of the maximum theoretical Lambertian limit of absorption. Light trapping 1 is an essential aspect in the design of solar cells based on thin absorbers, including both amor- phous/microcrystalline thin flms 2–4 and the recently emerging thin mono-crystalline silicon technologies 5,6 , as it allows for the absorption of the long-wavelength (near-bandgap) photons due to the extended path-length of light inside the thin semiconductor. Among a broad range of approaches proposed to realize light trapping, the scattering of light from subwavelength metallic nanoparticles, due to the localized surface plasmon reso- nance (LSPR) efect, is ofen considered a promising route 7,8 , with a theoretical possibility to overcome the 4n 2 limit 9 . In addition, the solid-state dewetting technique, commonly used for the fabrication of the metallic nano- structures 10,11 , gives additional advantages of low-cost, simplicity, direct scalability and compatibility with the industrial manufacturing processes. It has been demonstrated that such nanoparticles (NPs) incorporated in the so-called plasmonic back refector (PBR) confguration – consisting of fat silver mirror, aluminum doped zinc oxide (AZO) spacer layer and the NPs – used as a substrate for the deposition of the photovoltaic absorber, can provide efcient light trapping comparable to state-of-art random texturing 12,13 . 1 MATIS IMM-CNR, via S. Sofia 64, I-95123 Catania, Italy. 2 Dipartimento di Fisica e Astronomia, Università di Catania, via S. Sofa 64, I-95123 Catania, Italy. 3 Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, Prague, Czech Republic. 4 i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa and CEMOP/UNINOVA, Campus de Caparica, 2829-516 Caparica, Portugal. 5 Scuola Superiore di Catania, Università di Catania, via Valdisavoia 9, 95123 Catania, Italy. 6 Department of Energy, Information Engineering and Mathematical Models (DEIM), University of Palermo, Viale delle Scienze, Building 9, I-90128 Palermo, ITALY. Correspondence and requests for materials should be addressed to S.M. (email: seweryn.morawiec@ct.infn.it) or I.C. (email: isodiana.crupi@unipa.it) received: 25 June 2015 accepted: 12 February 2016 Published: 03 March 2016 opeN