Fully Inorganic Ruddlesden-Popper double Cl-I and triple Cl-Br-I Lead Halide Perovskite Nanocrystals
Quinten A. Akkerman a, Eva Bladt b, Sara Bals b, Liberato Manna a
a Istituto Italiano di Tecnologia (IIT), Genova, Italy, Via Morego, 30, Genova, Italy
b 2 EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
Roma, Italy, 2019 May 12th - 15th
Organizers: Prashant Kamat, Filippo De Angelis and Aldo Di Carlo
Poster, Quinten A. Akkerman, 256
Publication date: 11th February 2019

The vast majority of lead halide perovskite (LHP) nanocrystals (NCs) are currently based on either a single halide composition (CsPbCl3, CsPbBr3, and CsPbI3) or an alloyed mixture of bromide with either Cl or I [i.e., CsPb(Br:Cl)3 or CsPb(Br:I)3].1,2 Here, we present the synthesis as well as a detailed optical and structural study of two halide alloying cases that have not previously been reported for LHP NCs: Cs2PbI2Cl2 NCs and triple halide CsPb(Cl:Br:I)3 NCs.3 In the case of Cs2PbI2Cl2, we observe for the first time NCs with a fully inorganic Ruddlesden–Popper phase (RPP) crystal structure. Unlike the well-explored organic–inorganic RPP, here, the RPP formation is triggered by the size difference between the halide ions. These NCs exhibit a strong excitonic absorption, albeit with a weak photoluminescence quantum yield (PLQY). In the case of the triple halide CsPb(Cl:Br:I)3 composition, the NCs comprise a CsPbBr2Cl perovskite crystal lattice with only a small amount of incorporated iodide, which segregates at RPP planes’ interfaces within the CsPb(Cl:Br:I)3 NCs. Supported by density functional theory calculations and postsynthetic surface treatments to enhance the PLQY, we show that the combination of iodide segregation and defective RPP interfaces are most likely linked to the strong PL quenching observed in these nanostructures. In summary, this work demonstrates the limits of halide alloying in LHP NCs because a mixture that contains halide ions of very different sizes leads to the formation of defective RPP interfaces and a severe quenching of LHP NC’s optical properties.

© Fundació Scito
We use our own and third party cookies for analysing and measuring usage of our website to improve our services. If you continue browsing, we consider accepting its use. You can check our Cookies Policy in which you will also find how to configure your web browser for the use of cookies. More info