The inorganic halide perovskite CsPbI 3 has shown great promise for efficient solar cells, but the instability of its cubic phase remains a major challenge. We present a route for stabilizing the cubic α-phase of CsPbI 3 through the control of vacancy defects. Analysis of the ionic chemical potentials is performed within an ab initio thermodynamic formalism, including the effect of solution. It is found that cation vacancies lead to weakening of the interaction between Cs and PbI 6 octahedra in CsPbI 3 , with a decrease in the energy difference between the α- and δ-phases. Under I-rich growth conditions, which can be realized experimentally, we predict that the formation of cation vacancies can be controlled. Other synthetic strategies for cubic-phase stabilization include the growth of nanocrystals, surface capping ligands containing reductive functional groups, and extrinsic doping. Our analysis reveals mechanisms for polymorph stabilization that open a new pathway for structural control of halide perovskites.
Bibliographical noteFunding Information:
This work is supported as part of the fundamental research project “Design of Innovative Functional Materials for Energy and Environmental Application” (no. 2016-20) funded by the State Committee of Science and Technology, DPR Korea. The work in the UK has been supported by the Royal Society and the Leverhulme Trust.
© 2019 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films