Perovskites: Structure, Properties, and Applications in Modern Materials Science

Structure of Perovskites

Most perovskites share a general chemical formula of ABX₃, where:

• A and B are cations
• X is an anion.

The A-site cation is typically an alkaline earth metal (e.g., strontium, calcium, or barium) but may also be a rare earth metal such as lanthanum or yttrium. The B-site cation is commonly a transition metal such as titanium or iron. The X-site anion is most often oxygen, though other anions like iodide or chloride can also occupy this position.

In some cases, organic molecules can replace the metal cations or anions, resulting in hybrid perovskites. Because of this chemical flexibility, perovskite compositions can be finely tuned to achieve specific material characteristics, making them a remarkably versatile class of materials.

1. Solar Cells

Perovskite solar cells have emerged as a low-cost, high-efficiency alternative to conventional silicon-based photovoltaics. Perovskites act as semiconductors with a small electronic band gap, allowing them to efficiently absorb sunlight and generate charge carriers.

Their band gap can be tuned by modifying the chemical composition, enabling absorption across a wider range of the solar spectrum — including near-infrared light — and thus improving overall efficiency.

Fabrication
Perovskite solar cells can be manufactured using solution-based techniques, making them simpler and cheaper to produce than silicon solar cells. Their high absorption coefficient also means that thin perovskite layers can capture significant light, resulting in lightweight and flexible devices.

Materials
The most common materials used in perovskite solar cells are hybrid organic–inorganic lead halide perovskites, such as:

• Methylammonium lead iodide (CH₃NH₃PbI₃)

• Formamidinium lead iodide (HC(NH₂)₂PbI₃)

All-inorganic and mixed-halide perovskites are also being studied, though they are less prevalent in commercial use.

Challenges and Outlook
Key challenges remain around stability, moisture sensitivity, and interface optimisation. Active research continues to address these issues, and Goodfellow aims to contribute to these efforts by providing high-purity inorganic perovskite materials for laboratory and R&D use.

2. Catalysis

Perovskites also show significant potential in catalytic applications due to their:

• High surface area

• Tuneable redox chemistry

• Adjustable catalytic activity

They have been explored for use in oxidation, reduction, and reforming reactions, including:

• Hydrogen production (via steam reforming and water splitting)

• Pollutant removal from exhaust gases

• Selective oxidation of organic compounds

One major advantage of perovskite catalysts is their compositional tunability. By varying the material’s structure, morphology, and surface properties, researchers can design catalysts with high activity, selectivity, and durability.

Though research into catalytic mechanisms is ongoing, perovskites are increasingly recognised as promising materials for next-generation catalytic processes.

3. Sensors & Actuators

Many perovskites exhibit the piezoelectric effect, where mechanical stress generates an electrical charge. This phenomenon was first discovered in 1880 by Pierre and Jacques Curie, who observed that crystals such as quartz produced electric currents under pressure.

In perovskite materials, this effect arises from asymmetry in the crystal lattice, which causes charge separation when the material is deformed. Conversely, applying a voltage can induce mechanical motion, making perovskites useful for:

• Ultrasound transducers

• Precision actuators

• Vibration sensors

• Piezoelectric motors