The ease of halide ion exchange in metal halide nanocrystals offers an opportunity to utilize them in a layered or tandem fashion to achieve graded bandgap films. We have now successfully suppressed the halide ion exchange by capping CsPbBr3 and CsPbI3 nanocrystals with PbSO4–oleate to create a nanostructure assembly that inhibits the exchange of anions. Absorption measurements show that the nanocrystal assemblies maintain their identity as either CsPbBr3 or CsPbI3 for several days. Furthermore, the effect of PbSO4–oleate capping on the excited state dynamics has also been elucidated. The effectiveness of PbSO4–oleate capping of lead halide perovskite nanocrystals offers new opportunities to overcome the challenges of halide ion exchange and aid toward the tandem design of perovskite light-harvesting assemblies.
Ravi VK, Scheidt RA, Nag A, Kuno M, Kamat PV (2018) To Exchange or Not to Exchange. Suppressing Anion Exchange in Cesium Lead Halide Perovskites with PbSO4–Oleate Capping. ACS Energy Letters 3: 1049–1055. Available: http://dx.doi.org/10.1021/acsenergylett.8b00380.
V.K.R. acknowledges the Department of Science and Technology (DST), Govt. of India and the 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. acknowledges 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. M.K. acknowledges support of the Division of Materials Sciences and Engineering Office of Basic Energy Sciences of the U.S. Department of Energy through Award DE-SC0014334 for carrying out the analysis and discussion of results. This is contribution number NDRL No. 5204 from the Notre Dame Radiation Laboratory.