Abstract
All-inorganic cesium lead halide perovskite nanocrystals are extensively studied because of their outstanding optoelectronic properties. Being of a cubic shape and typically featuring a narrow size distribution, CsPbX3 (X = Cl, Br, and I) nanocrystals are the ideal starting material for the development of homogeneous thin films as required for photovoltaic and optoelectronic applications. Recent experiments reveal spontaneous merging of drop-casted CsPbBr3 nanocrystals, which is promoted by humidity and mild-temperature treatments and arrested by electron beam irradiation. Here, we make use of atom-resolved annular dark-field imaging microscopy and valence electron energy loss spectroscopy in a state-of-the-art low-voltage monochromatic scanning transmission electron microscope to investigate the aggregation between individual nanocrystals at the atomic level. We show that the merging process preserves the elemental composition and electronic structure of CsPbBr3 and takes place between nanocrystals of different sizes and orientations. In particular, we reveal seamless stitching for aligned nanocrystals, similar to that reported in the past for graphene flakes. Because the crystallographic alignment occurs naturally in drop-casted layers of CsPbX3 nanocrystals, our findings constitute the essential first step toward the development of large-area nanosheets with band gap energies predesigned by the nanocrystal choice - the gateway to large-scale photovoltaic applications of inorganic perovskites.
Original language | English |
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Pages (from-to) | 5984-5991 |
Number of pages | 8 |
Journal | ACS Applied Materials and Interfaces |
Volume | 10 |
Issue number | 6 |
DOIs | |
Publication status | Published - 14 Feb 2018 |
Funding
C.d.W., L.G., and T.G. acknowledge the Dutch Technology Foundation STW, which is part of the Netherlands Organisation for Scientific Research (NWO) for financial support. J.L. and K.S. work has been financed by JST-ACCEL and JSPS KAKENHI (JP16H06333 and P16823). E.v.H. thanks the Foundation for Fundamental Research on Matter (FOM) (V0714M-13MV60) from the Netherlands Organization for Scientific Research (NWO) for funding. Y.F. and T.G. thank Osaka University for International Joint Research Promotion Program.
Funders | Funder number |
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JST-ACCEL | |
Japan Society for the Promotion of Science | JP16H06333, P16823 |
Stichting voor Fundamenteel Onderzoek der Materie | V0714M-13MV60 |
Nederlandse Organisatie voor Wetenschappelijk Onderzoek | |
Stichting voor de Technische Wetenschappen | |
Osaka University |
Keywords
- EELS
- high-resolution TEM
- inorganic perovskites
- merging
- nanocrystals
- seamless stitching