title: Engineering Interfacial Charge Transfer in CsPbBr3Perovskite Nanocrystals by Heterovalent Doping.
abstract: Since compelling device efficiencies of perovskite solar cells have been achieved, investigative efforts have turned to understand other key challenges in these systems, such as engineering interfacial energy-level alignment and charge transfer (CT). However, these types of studies on perovskite thin-film devices are impeded by the morphological and compositional heterogeneity of the films and their ill-defined surfaces. Here, we use well-defined ligand-protected perovskite nanocrystals (NCs) as model systems to elucidate the role of heterovalent doping on charge-carrier dynamics and energy level alignment at the interface of perovskite NCs with molecular acceptors. More specifically, we develop an in situ doping approach for colloidal CsPbBr3perovskite NCs with heterovalent Bi3+ions by hot injection to precisely tune their band structure and excited-state dynamics. This synthetic method allowed us to map the impact of doping on CT from the NCs to different molecular acceptors. Using time-resolved spectroscopy with broadband capability, we clearly demonstrate that CT at the interface of NCs can be tuned and promoted by metal ion doping. We found that doping increases the energy difference between states of the molecular acceptor and the donor moieties, subsequently facilitating the interfacial CT process. This work highlights the key variable components not only for promoting interfacial CT in perovskites, but also for establishing a higher degree of precision and control over the surface and the interface of perovskite molecular acceptors.
authors.affiliation: KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Raihana
authors.initials: R
authors.lastname: Begum
authors.affiliation: KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Manas R
authors.initials: MR
authors.lastname: Parida
authors.affiliation: KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Ahmed L
authors.initials: AL
authors.lastname: Abdelhady
authors.affiliation: KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Banavoth
authors.identifier: 0000-0002-7806-2274
authors.initials: B
authors.lastname: Murali
authors.affiliation: KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Noktan M
authors.initials: NM
authors.lastname: Alyami
authors.affiliation: KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Ghada H
authors.initials: GH
authors.lastname: Ahmed
authors.affiliation: KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Mohamed Nejib
authors.initials: MN
authors.lastname: Hedhili
authors.affiliation: KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Osman M
authors.identifier: 0000-0002-3428-1002
authors.initials: OM
authors.lastname: Bakr
authors.affiliation: KAUST Solar Center, Division of Physical Sciences and Engineering and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Omar F
authors.identifier: 0000-0001-8500-1130
authors.initials: OF
authors.lastname: Mohammed