The term perovskites refers to a vast range of mineral structures that share the same geometric arrangement as the ions in the natural perovskite mineral calcium titanate (CaTiO3). Replacing the calcium, titanium, and oxygen with ions of other elements, or with carbon-based ‘organic’ chemical groups, generates new hybrid perovskites with many useful properties, such as those needed for producing solar cells.
“We focus our review specifically on ways to control the crystal structures and increase efficiency by enhancing the transport of charge through the perovskite materials,” Aziz explains.
Aziz’s interest in solar cells came naturally to her, as she is from Malaysia, where there is abundant sunshine all year round. Her focus on perovskites was stimulated some years ago by increasing excitement around the field, which led one prestigious journal to hail perovskite solar cells as one of the top ten breakthroughs of 2013. Global research interest and progress has continued to build steadily since then.
To act as a solar cell, a material must contain electrons that can be kicked out of place by the energy of sunlight, leaving regions appropriately called ‘holes’ behind. The electrons can be fed through a circuit, creating the useful electric current, before ultimately recombining with the holes, which themselves need to move through the materials for maximum efficiency.
Aziz and her co-authors explain that perovskites are proving especially suitable for this task, and can now almost match the energy-converting efficiency of conventional silicon-based solar cells. But the perovskites offer the great advantage of being simpler and less expensive to manufacture, showing potential to transform the economic feasibility of solar power.