The suppression of halide ion exchange between CsPbBr3 and CsPbI3 nanocrystals achieved through capping with PbSO4–oleate has enabled us to deposit different perovskite nanocrystals as aligned arrays on the electrode surfaces without intermixing of species. The electrophoretic deposition of PbSO4–oleate-capped CsPbX3 (X = Cl, Br, I) nanocrystals suspended in hexane solution on mesoscopic TiO2 films allows the design of controlled architecture with single or multiple layers of perovskite films. The hierarchy in the assembly of these nanocrystals is seen first through the linearly organized nanocrystals in hexane followed by the deposition of larger linear rods ∼500 nm in length. Since most of the photophysical properties of nanocrystals are retained in these aligned arrays, we can design films with tunable luminescence including white color. The electrophoretic deposition of layered films of perovskites in a controlled fashion opens up new ways to design tandem perovskite solar cells and tunable display devices.
Ravi VK, Scheidt RA, DuBose J, Kamat PV (2018) Hierarchical Arrays of Cesium Lead Halide Perovskite Nanocrystals through Electrophoretic Deposition. Journal of the American Chemical Society 140: 8887–8894. Available: http://dx.doi.org/10.1021/jacs.8b04803.
We thank Prof. Angshuman Nag of IISER, Pune, for helpful discussions. V.K.R. acknowledges the Department of Science and Technology (DST), Govt. of India, and Indo-U.S. Science and Technology Forum (IUSSTF) for the Bhaskara Advanced Solar Energy (BASE) internship and IISER Pune for a graduate research fellowship. R.A.S. acknowledges the support of King Abdullah University of Science and Technology (KAUST) through Award OCRF-2014-CRG3-2268. P.V.K. and J.D.B. acknowledge the support of the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences of the U.S. Department of Energy, through award DE-FC02-04ER15533. This is contribution number NDRL No. 5216 from the Notre Dame Radiation Laboratory.