Nanometre- and micrometre-scale textures on solar cell surfaces are best known for reducing reflection and trapping more light. New work shows these tiny surface patterns can also help perovskite solar cells in other, less obvious ways. Researchers report that textures can make solution films spread better, improve the crystal quality of the perovskite layer, help electrical charges leave the device more efficiently, and even reduce stress in flexible devices.

One clear benefit is improved wetting when perovskite solution is deposited on a textured surface. In silicon–perovskite tandem devices, a sinusoidal nanotexture on the silicon bottom cell helped perovskite solution cover the surface during spin coating. The study by Tockhorn and colleagues found that the share of unusable samples with large holes dropped from about 50% on flat substrates to below 5% on nanotextured ones. Researchers have used hierarchical textures—large pyramids with nano‑scale features, black‑silicon needles, or specially patterned inverted pyramids—to make solution films conformal and to raise fabrication yield. In some cases changing how a contact layer is made (for example evaporating a self‑assembled monolayer instead of spin coating it) also helped wetting on flat surfaces.

Textures also seem to guide how perovskite crystals grow. Several groups report larger grain sizes, preferred crystal orientations (for example grains aligned so boundaries run vertically through the layer), and fewer signs of unwanted lead‑iodide phases when films form on textured substrates. In one study, perovskite grains on a textured aluminium‑doped zinc oxide electrode were on average twice as large and showed narrower X‑ray diffraction peaks than on flat electrodes. Other reports describe reduced phase segregation under light soak and removal of PbI2 signals in X‑ray data, which point to more uniform films.