Articolo in rivista, 2014, ENG, 10.1016/j.tsf.2013.10.060

Surface chemistry of arenethiolate-capped PbS quantum dots and application as colloidally stable photovoltaic ink

Giansante C.[ 1,2 ]; Carbone L.[ 3 ]; Giannini C.[ 4 ] ; Altamura D.[ 4 ] ; Ameer Z.[ 5 ] ; Maruccio G.[ 1,2,5 ] ; Loiudice A.[ 1 ]; Belviso M.R.[ 2 ] ; Cozzoli P.D.[ 2,5 ]; Rizzo A.[ 1,2 ]; Gigli G.[ 1,2,5 ]

[ 1 ] Ist Italiano Tecnol, UNILE, Ctr Biomol Nanotechnol, I-73010 Arnesano, LE, Italy [ 2 ] CNR, NNL, Ist Nanosci, I-73100 Lecce, Italy [ 3 ] UOS Pisa, IPCF CNR, I-56124 Pisa, Italy [ 4 ] IC CNR, Ist Cristallog, I-70126 Bari, Italy [ 5 ] Univ Salento, Dipartimento Matemat & Fis E de Giorgi, I-73100 Lecce, Italy

Suitable post-synthesis surface modification of lead-chalcogenide quantum dots (QDs) is crucial to enable their integration in photovoltaic devices. We have developed a solution-phase ligand exchange strategy that exploits arenethiolate anions to replace the pristine oleate ligands on PbS QDs, while preserving the long-term colloidal stability of QDs and allowing their solution-based processability into photoconductive thin-films. Complete QD surface modification is demonstrated by IR spectroscopy analysis, whereas UV-Vis-NIR Absorption Spectroscopy provides quantitative evaluation of stoichiometry and thermodynamic stability of the resulting system. Arenethiolate ligands permit to reduce the inter-particle distance in PbS QD solids, leading to a drastic improvement of the photoinduced charge transport properties. Therefore, smooth dense-packed thin-films of arenethiolate-capped PbS QDs obtained via a single solution-processing step are integrated in heterojunction solar cells: such devices generate remarkable photocurrent densities (14 mA cm(-2)) and overall efficiencies (1.85%), which are outstanding for a single PbS QD layer. Solution-phase surface modification of QDs thus represents an effective intermediate step towards low-cost processing for all-inorganic and hybrid organic/inorganic QD-based photovoltaics.

Thin solid films (Print) 560 , pp. 2–9

Keywords

Colloidal quantum dots, Organic/inorganic interface, Photovoltaic ink, Solution-phase ligand exchange, Solution-processing

CNR authors

Cozzoli Pantaleo Davide, Gigli Giuseppe, Maruccio Giuseppe, Belviso Maria Rosaria, Giansante Carlo, Giannini Cinzia, Carbone Luigi, Rizzo Aurora, Altamura Davide

CNR institutes

IC – Istituto di cristallografia, NANOTEC – Istituto di Nanotecnologia, NANO – Istituto Nanoscienze