title: Efficient eco-friendly inverted quantum dot sensitized solar cells.
abstract: Recent progress in quantum dot (QD) sensitized solar cells has demonstrated the possibility of low-cost and efficient photovoltaics. However, the standard device structure based on n-type materials often suffers from slow hole injection rate, which may lead to unbalanced charge transport. We have fabricated efficient p-type (inverted) QD sensitized cells, which combine the advantages of conventional QD cells with p-type dye sensitized configurations. Moreover, p-type QD sensitized cells can be used in highly promising tandem configurations with n-type ones. QDs without toxic Cd and Pb elements and with improved absorption and stability were successfully deposited onto mesoporous NiO electrode showing good coverage and penetration according to morphological analysis. Detailed photophysical charge transfer studies showed that high hole injection rates (108s-1) observed in such systems are comparable with electron injection in conventional n-type QD assemblies. Inverted solar cells fabricated with various QDs demonstrate excellent power conversion efficiencies of up to 1.25%, which is 4 times higher than the best values for previous inverted QD sensitized cells. Attempts to passivate the surface of the QDs show that traditional methods of reduction of recombination in the QD sensitized cells are not applicable to the inverted architectures.
authors.affiliation: Univ. Grenoble Alpes , INAC-SPRAM , F-38000 Grenoble , France . Email: dmitry.aldakov@cea.fr; CNRS , INAC-SPRAM , F-38000 Grenoble , France ; CEA , INAC-SPRAM , F-38000 Grenoble , France.
authors.forename: Jinhyung
authors.initials: J
authors.lastname: Park
authors.affiliation: Organic Semiconductor Centre , SUPA , School of Physics and Astronomy , University of St Andrews , North Haugh, St Andrews , Fife , UK . Email: idws@st-andrews.ac.uk.
authors.forename: Muhammad T
authors.initials: MT
authors.lastname: Sajjad
authors.affiliation: CEA , INAC-SP2M , LEMMA , F-38000 Grenoble , France.
authors.forename: Pierre-Henri
authors.initials: PH
authors.lastname: Jouneau
authors.affiliation: Organic Semiconductor Centre , SUPA , School of Physics and Astronomy , University of St Andrews , North Haugh, St Andrews , Fife , UK . Email: idws@st-andrews.ac.uk.
authors.forename: Arvydas
authors.initials: A
authors.lastname: Ruseckas
authors.affiliation: Univ. Grenoble Alpes , INAC-SPRAM , F-38000 Grenoble , France . Email: dmitry.aldakov@cea.fr; CNRS , INAC-SPRAM , F-38000 Grenoble , France ; CEA , INAC-SPRAM , F-38000 Grenoble , France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Faure-Vincent
authors.affiliation: Organic Semiconductor Centre , SUPA , School of Physics and Astronomy , University of St Andrews , North Haugh, St Andrews , Fife , UK . Email: idws@st-andrews.ac.uk.
authors.forename: Ifor D W
authors.initials: ID
authors.lastname: Samuel
authors.affiliation: Univ. Grenoble Alpes , INAC-SPRAM , F-38000 Grenoble , France . Email: dmitry.aldakov@cea.fr; CNRS , INAC-SPRAM , F-38000 Grenoble , France ; CEA , INAC-SPRAM , F-38000 Grenoble , France.
authors.forename: Peter
authors.initials: P
authors.lastname: Reiss
authors.affiliation: Univ. Grenoble Alpes , INAC-SPRAM , F-38000 Grenoble , France . Email: dmitry.aldakov@cea.fr; CNRS , INAC-SPRAM , F-38000 Grenoble , France ; CEA , INAC-SPRAM , F-38000 Grenoble , France.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Aldakov