Bertille Martinez, Dylan Amelot, Sang-Soo Chee, Abdelkarim Ouerghi, Mayank Goyal, Francesco Andrea Bresciani, Hervé Cruguel, Charlie Gréboval, Nadine Witkowski, Angshuman Nag, Xiang Zhen Xu, Emmanuel Lhuillier, Nicolas Casaretto, Mathieu G. Silly, Junling Qu, Audrey Chu, Clément Livache, Prachi Rastogi, Christophe Méthivier, Physico-chimie et dynamique des surfaces (INSP-E6), Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Indian Institute of Science Education and Research Pune (IISER Pune), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique et d'Etude des Matériaux (LPEM), ESPCI ParisTech-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Réactivité de Surface (LRS), Centre de Nanosciences et Nanotechnologies (C2N (UMR_9001)), Université Paris-Sud - Paris 11 (UP11)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), ANR-11-IDEX-0004-02/10-LABX-0067,MATISSE,MATerials, InterfaceS, Surfaces, Environment(2011), ANR: copin, ANR: frontal, ANR: graskop,graskop, European Project: 756225,blackQD, Laboratoire de Physique et d'Etude des Matériaux (UMR 8213) (LPEM), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), ANR-11-IDEX-0004,SUPER,Sorbonne Universités à Paris pour l'Enseignement et la Recherche(2011), ANR-19-CE24-0022,COPIN,Détecteur plasmonique à nanoCristaux colloïdaux: une nouvelle filière pour l'OPtoélectronique INfrarouge(2019), ANR-19-CE09-0017,FRONTAL,Nanocristaux Colloïdaux Dopés Infrarouges(2019), and ANR-19-CE09-0026,GRaSkop,Tuning Giant Rashba Spin-Orbit Coupling in Polar Single Layer Transition Metal Dichalcogenides(2019)
International audience; Lead halide perovskite nanocrystals have attracted attention in the field of nanocrystal-based light-emitting diode and solar cells, because their devices showed high performances in only a few years. Among them, CsPbI3 is a promising candidate for solar cell design in spite of a too wide band gap and severe structural stability issue. Its hybrid organic–inorganic counterpart (NH2)2CHPbI3 (FAPI), where the Cs is replaced with formamidinium (FA), presents a smaller band gap and also an improved structural stability. Here, we have investigated the energy landscape of pristine FAPI, and the interface of FAPI with electron and hole selective layers using transport, photoemission, and noncontact surface photovoltage by means of time-resolved photoemission. We have found from transport and photoemission that its Fermi level is deeply positioned in the band gap, enabling the material to be almost intrinsic. Time-resolved photoemission has revealed that the interface of pristine FAPI is bended toward downward side, which is consistent with a p-type nature for the interface (i.e., hole as majority carrier). Using TiOx and MoOx contacts, as a model for the electron and hole transport layer, respectively, allows the electron transfer from the TiOx to the FAPI and from the FAPI to the MoOx. The latter is revealed by time-resolved photoemission showing inverted band bending for the two interfaces. From these results, we clearly present the energy landscape of FAPI and its interfaces with TiOx and MoOx in the dark and under illumination. These insights are of utmost interest for the future design of FAPI-based solar cell.