title: Solid-state colloidal CuInS2quantum dot solar cells enabled by bulk heterojunctions.
abstract: Colloidal copper indium sulfide (CIS) nanocrystals (NCs) are Pb- and Cd-free alternatives for use as absorbers in quantum dot solar cells. In a heterojunction with TiO2, non-annealed ligand-exchanged CIS NCs form solar cells yielding a meager power conversion efficiency (PCE) of 0.15%, with photocurrents plummeting far below predicted values from absorption. Decreasing the amount of zinc during post-treatment leads to improved mobility but marginal improvement in device performance (PCE = 0.30%). By incorporating CIS into a porous TiO2network, we saw an overall drastic improvement in device performance, reaching a PCE of 1.16%, mainly from an increase in short circuit current density (Jsc) and fill factor (FF) and a 10-fold increase in internal quantum efficiency (IQE). We have determined that by moving from a bilayer to a bulk heterojunction architecture, we have reduced the trap-assisted recombination as seen in changes in the ideality factor, the intensity dependence of the photocurrent and transient photocurrent (TPC) and photovoltage (TPV) characteristics.
authors.affiliation: ICFO, Institute of Photonic Sciences, The Barcelona Institute of Science and Technology, Castelldefels 08860, Spain. gerasimos.konstantatos@icfo.es.
authors.forename: D
authors.initials: D
authors.lastname: So
authors.affiliation: ICFO, Institute of Photonic Sciences, The Barcelona Institute of Science and Technology, Castelldefels 08860, Spain. gerasimos.konstantatos@icfo.es.
authors.forename: S
authors.initials: S
authors.lastname: Pradhan
authors.affiliation: ICFO, Institute of Photonic Sciences, The Barcelona Institute of Science and Technology, Castelldefels 08860, Spain. gerasimos.konstantatos@icfo.es and Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain.
authors.forename: G
authors.initials: G
authors.lastname: Konstantatos