multicrystalline

Multicrystalline refers to a material that is composed of many small crystals, or grains, each with its own distinct lattice orientation. The boundaries between grains, known as grain boundaries, influence properties such as electrical conductivity, optical behavior, and mechanical strength. Multicrystalline materials contrast with single-crystal (monocrystalline) materials, which have a continuous crystal lattice without grain boundaries.

In the context of energy and electronics, multicrystalline silicon is the most common multicrystalline material. It is produced by melting silicon and allowing it to solidify into cast ingots containing numerous randomly oriented crystals. The ingots are sliced into wafers for photovoltaic cells. The grain structure lowers production cost compared with monocrystalline silicon, but grain boundaries can introduce recombination centers that reduce carrier lifetimes and solar-cell efficiency. Consequently, multicrystalline silicon modules typically have lower efficiency than monocrystalline silicon modules, though their lower cost supports widespread use in commercial solar panels.

Other multicrystalline materials are used across industry, including metals such as copper and aluminum alloys, where polycrystalline grain structure governs mechanical properties and workability.

Manufacturing approaches for multicrystalline materials aim to control grain size and boundary characteristics through casting, directional solidification, and annealing, or through alloying and subsequent thermal treatments. Applications extend beyond photovoltaics to metallurgy, electronics, and optics, wherever polycrystalline materials offer a favorable balance of performance and cost.