Plasmonic light trapping leads to responsivity increase in colloidal quantum dot photodetectors

We report broadband responsivity enhancement in PbS colloidal quantum dot (CQDs) photoconductive photodetectors due to absorption increase offered by a plasmonic scattering layer of Ag metal nanoparticles. Responsivity enhancements are observed in the near infrared with a maximum 2.4-fold increase near the absorption band edge of 1 lm for 400 nm thick devices. Additionally, we study the effect of the mode structure on the efficiency of light trapping provided by random nanoparticle scattering in CQD films and provide insights for plasmonic scattering enhancement in CQD thin films.This research has been partially supported by Fundacio´ Privada Cellex Barcelona. We also acknowledge support from European Commission’s Seventh Framework Programme for Research under contract PIRG06-GA-2009-256355

Solution Processed Bismuth Sulfide Nanowire Array Core/Silver Sulfide Shell Solar Cells

Low bandgap inorganic semiconductor nanowires have served as building blocks in solution processed solar cells to improve their power conversion capacity and reduce fabrication cost. In this work, we first reported bismuth sulfide nanowire arrays grown from colloidal seeds on a transparent conductive substrate via mild aqueous chemistry and demonstrated a novel core–shell nanowire architecture to enhance the photovoltaic performances of hybrid solar cells. We found that the bismuth sulfide nanowire core/silver sulfide shell structure reduces the interfacial charge recombination between the core and a hole transporter layer and enables efficient charge separation in a type-II core–shell heterojunction. The bismuth sulfide nanowire core/silver sulfide shell combined with 2,2′,7,7′-tetrakis­(<i>N</i>,<i>N</i>-di-<i>p</i>-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) reached solar-to-electricity power conversion efficiency of 2.5%, advancing the field of solution processed solar cells based on environmentally friendly metal chalcogenide semiconductors