Tag Archives: perovskites

Perovskite Could Convert Up To 44% Of Light Into Electricity

Perovskites are a family of crystals that show promising properties for applications in nano-technology. However, one useful property that until now was unobserved in perovskites is so-called carrier multiplication – an effect that makes materials much more efficient in converting light into electricity. New research, led by   (UvA-IoP) physicists Dr Chris de Weerd and Dr Leyre Gomez from the group of Prof. Tom Gregorkiewicz, has now shown that certain perovskites in fact do have this desirable propertyCrystals are configurations of atoms, molecules or ions, that are ordered in a structure that repeats itself in all directions. We have all encountered some crystals in everyday life: ordinary salt, diamond and even snowflakes are examples. What is perhaps less well-known is that certain crystals show very interesting properties when their size is not that of our everyday life but that of nanometers – a few billionths of a meter.

Perovskites – named after 19th century Russian mineralogist Lev Perovski – form a particular family of materials that all share the same crystal structure. These perovskites have many desirable electronic properties, making them useful for constructing for example LEDs, TV-screens, solar cells and lasers. A property which so far had not been shown to exist in perovskites is carrier multiplication. When semiconductors – in solar cells, for example – convert the energy of light into electricity, this is usually done one particle at a time: a single infalling photon results in a single excited electron (and the corresponding ‘hole’ where the electron used to be) that can carry an electrical current. However, in certain materials, if the infalling light is energetic enough, further electron-hole pairs can be excited as a result; it is this process that is known as carrier multiplication.

Until now, carrier multiplication had not been reported for perovskites. That we have now found it is of great fundamental impact on this upcoming material. For example, this shows that perovskite nanocrystals can be used to construct very efficient photodetectors, and in the future perhaps solar cells”, says De Weerd, who successfully defended her PhD thesis based on this and other research last week.

When carrier multiplication occurs, the conversion from light into electricity can become much more efficient. For example, in ordinary solar cells there is a theoretical limit (the so-called Shockley-Queisser limit) on the amount of energy that can be converted in this way: at most a little over 33% of the solar power gets turned into electrical power. In semiconductor nanocrystals that feature the carrier multiplication effect, however, a maximum efficiency of up to 44% is predicted.

The paper in which the researchers report on their findings was published in Nature Communications this week.

Source: http://iop.uva.nl/