(99a) Nanocrystal Doping Stabilizes the Perovskite Phase of Cesium Lead Iodide | AIChE

(99a) Nanocrystal Doping Stabilizes the Perovskite Phase of Cesium Lead Iodide


Fafarman, A. - Presenter, Drexel University
Dastidar, S., Drexel University
Egger, D. A., Weizmann Institute of Science
Tan, L. Z., University of Pennsylvania
Cromer, S. B., Drexel University
Dillon, A. D., Drexel University
Liu, S., University of Pennsylvania
Rappe, A., University of Pennsylvania
All-inorganic, perovskite-phase cesium lead iodide is a promising material for photovoltaics. However, under ambient conditions it rapidly transforms to a non-functional, so-called yellow phase. Here we demonstrate more than two orders of magnitude improvement in the stability of nanostructured perovskite-phase cesium lead iodide thin films through a nanocrystal doping approach. The doped, functional perovskite phase is synthesized by co-assembling cesium lead iodide nanocrystals with cesium lead chloride dopant nanocrystals. The resulting doped nanocrystal solid is subsequently fused into a polycrystalline thin film by chemically-induced, room-temperature sintering. This process ensures nanometer-scale mixing even at compositions that exceed the bulk miscibility of the two constituents. Spectroscopy and X-ray diffraction indicate that some of this chloride is further dispersed during sintering and a polycrystalline mixed phase is formed. By comparison to DFT-calculated values, the relative change in band gap and the lattice contraction are shown to be consistent with a Cl:I ratio of a few percent in the mixed phase.