Perovskite solar cells are causing a buzz in the world of photovoltaics. We explore what perovskites are and how they work, while keeping scientific jargon to a minimum.
What are perovskite solar cells?
Perovskite solar cells are a family of materials with a specific crystal structure, named after the mineral with that structure.
Perovskites are an entirely new materials science built around some 10 or more metallic elements that form a particular crystalline form, all of which exhibit photovoltaic (PV) properties. This science now has one foot in academia and the other in the real world of industry.
Perovskite solar cells have attracted interest because, unlike silicon solar cells, they can be mass-produced through roll-to-roll processing. Additionally, they are light and colourful, with the versatility to be used in non-traditional settings such as windows and contoured roofs.
Beyond solar applications, perovskites have also shown promise in a number of different application spaces. For example, they are being explored for use as radiation detectors.
Their tunable bandgap, large light absorption coefficient, large mobility, and long carrier recombination lifetime, while good properties for PV applications, also make them useful in both imaging and spectroscopy applications across a wide energy range. The solution processability of these materials and ease of manufacturing have also excited the detector community.
Other potential applications for halide perovskite solar cells are as emitters; for example as LEDs in solid-state lighting, and various display applications.
When used to create solar cells, perovskites have shown potential for high performance and low production costs.
How do perovskites work?
Prof Henry Snaith, co-founder and Chief Scientific Officer at Oxford PV, explained how his team collaborated with Tsutomu Miyasaka and learned the recipe of how to make perovskites. “What we found is that if we sandwiched that layer of polycrystalline perovskite… between two electrodes, modified to allow current to flow in one direction, we found quickly that we could secure really high efficiencies.”
This sandwich structure of perovskite cells is what really allows for greater efficiency to be achieved said Prof Snaith.
The Clean Energy Institute, Univerisity of Washington puts it this way: “All photovoltaic solar cells rely on semiconductors — materials in the middle ground between electrical insulators such as glass and metallic conductors such as copper — to turn the energy from light into electricity. Light from the sun excites electrons in the semiconductor material, which flow into conducting electrodes and produce electric current.”
Scientists have harnessed the tunability of perovskites to create semiconductors with similar properties to silicon. Because of the compositional flexibility of perovskites, they can also be tuned to ideally match the sun’s spectrum.
For a more in-depth discussion about perovskites and how they are changing the solar landscape through a variety of innovative applications, listen to this Energy Transitions podcast: Perovskite – Exploring solar’s next breakthrough.