High Chloride Doping Levels Stabilize the Perovskite Phase of Cesium Lead Iodide
- 13 May 2016
- journal article
- research article
- Published by American Chemical Society (ACS) in Nano Letters
- Vol. 16 (6), 3563-3570
- https://doi.org/10.1021/acs.nanolett.6b00635
Abstract
Cesium lead iodide possesses an excellent combination of band gap and absorption coefficient for photovoltaic applications in its perovskite phase. However, this is not its equilibrium structure under ambient conditions. In air, at ambient temperature, it rapidly transforms to a non-functional, so-called yellow phase. Here we show that chloride doping, particularly at levels near the solubility limit for chloride in a cesium lead iodide host, provides a new approach to stabilizing the functional perovskite phase. In order to achieve high doping levels, we first co-deposit colloidal nanocrystals of pure cesium lead chloride and cesium lead iodide, thereby ensuring nanometer-scale mixing even at compositions that potentially exceed the bulk miscibility of the two phases. The resulting nanocrystal solid is subsequently fused into a polycrystalline thin film by chemically-induced, room-temperature sintering. Spectroscopy and X-ray diffraction indicate that the chloride is further dispersed during sintering and a polycrystalline mixed phase is formed. Using density functional theory (DFT) methods in conjunction with nudged elastic band techniques, low-energy pathways for interstitial chlorine diffusion into a majority-iodide lattice were identified, consistent with the facile diffusion and fast halide exchange reactions observed. By comparison to DFT-calculated values (with the PBE exchange-correlation functional), 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. At these incorporation levels, the half-life of the functional perovskite phase in a humid atmosphere increases by more than an order of magnitude.Keywords
Funding Information
- Carnegie Institution of Washington
- Basic Energy Sciences (DE-FG02-07ER46431)
- Weizmann Institute of Science
- Austrian Science Fund (J3608-N20)
- Office of Naval Research (N00014-14-1-0761)
- Drexel University
This publication has 62 references indexed in Scilit:
- Hybrid organic—inorganic perovskites: low-cost semiconductors with intriguing charge-transport propertiesNature Reviews Materials, 2016
- Inorganic caesium lead iodide perovskite solar cellsJournal of Materials Chemistry A, 2015
- High-performance photovoltaic perovskite layers fabricated through intramolecular exchangeScience, 2015
- Temperature- and Component-Dependent Degradation of Perovskite Photovoltaic Materials under Concentrated SunlightThe Journal of Physical Chemistry Letters, 2015
- Study on the stability of CH3NH3PbI3films and the effect of post-modification by aluminum oxide in all-solid-state hybrid solar cellsJournal of Materials Chemistry A, 2013
- Chemical Management for Colorful, Efficient, and Stable Inorganic–Organic Hybrid Nanostructured Solar CellsNano Letters, 2013
- Efficient Hybrid Solar Cells Based on Meso-Superstructured Organometal Halide PerovskitesScience, 2012
- Layered organic–inorganic hybrid perovskites: structure, optical properties, film preparation, patterning and templating engineeringCrystEngComm, 2010
- Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic CellsJournal of the American Chemical Society, 2009
- Crystal Structure and Photoconductivity of Cæsium PlumbohalidesNature, 1958