Advanced Topic 714 of 1102 Inorganic Chemistry
Perovskites
ABX3 structures used in solar cells and ferroelectrics.
In-depth explanation of Perovskites
Perovskites have the general formula ABX3, in which the large A cation sits in a site coordinated by 12 X anions and the smaller B cation sits in an octahedron of X anions. The Goldschmidt tolerance factor predicts whether a given combination of ion sizes will adopt this structure. Oxides such as BaTiO3 are ferroelectric, with a spontaneous polarization that can be switched by an electric field, which is used in capacitors and sensors. Hybrid lead halide perovskites, such as CH3NH3PbI3, are efficient light absorbers in solar cells, with laboratory efficiencies above 25 percent.
Going deeper: Perovskites
Key ideas: ABX3 structure, named after CaTiO3. A is a large cation in the cube center with coordination number 12, B a smaller cation in an octahedral site (corner BX6), and X is oxide or halide. Goldschmidt tolerance factor t = (rA + rX) divided by square root 2 (rB + rX); stable cubic for about 0.9 to 1.0. Examples: BaTiO3 ferroelectric, YBa2Cu3O7 related, and methylammonium lead iodide used in solar cells with efficiencies above 25 percent.
Common mistakes and connections: Students forget distortions: tilting of octahedra when t is lower gives lower symmetry, which is key to ferroelectricity. Halide perovskites are unstable with moisture and contain toxic lead. Atom counting: 1 A, 1 B, and 3 X per cell. Links to photovoltaic materials, superconductors, solid state structure and ionic radii.
Visualization of Perovskites
CsCl-type cubic packing relates to the perovskite ABX3 structure, where a large cation sits in the centre of a cube of corner-sharing octahedra. The interactive lesson shows this as a live animation or chart.
Worked example and use case
BaTiO3 has a spontaneous polarization below its Curie temperature of about 120 degrees C.
Frequently asked questions about Perovskites
What is Perovskites?
ABX3 structures used in solar cells and ferroelectrics.
Is Perovskites a beginner, intermediate or advanced topic?
Perovskites is a advanced topic in Inorganic Chemistry. It builds on beginner and intermediate topics, so review those first if needed.
What should I learn before Perovskites?
Study these earlier topics in Inorganic Chemistry first: Zintl Phases, Cluster Compounds, Solid State Inorganic Structures.
What comes after Perovskites?
The next topics in Inorganic Chemistry are Metal-Organic Frameworks and Nanomaterials.
Can I practise Perovskites with quizzes?
Yes. The interactive lesson includes a self-check question on Perovskites, and the Inorganic Chemistry quiz draws on every topic in this area.
Where Perovskites fits in Inorganic Chemistry
Perovskites is topic 99 of 113 in Inorganic Chemistry.