Efficient light conversion with perovskite nanocrystals

October 11, 2018, University of Amsterdam
Perovskite lattice. Credit: Wikimedia Commons.

Perovskites are a family of crystals that show promising properties for applications in nanotechnology. However, a property called carrier multiplication, an effect that makes materials much more efficient in converting light into electricity, has not been observed in perovskites. New research, led by UvA-IoP physicists Dr. Chris de Weerd and Dr. Leyre Gomez from the group of Prof. Tom Gregorkiewicz, now reports that certain perovskites do have this desirable property.

Crystals are configurations of atoms, molecules or ions ordered in a structure that repeats itself in all directions. Examples include ordinary salt, diamonds and snowflakes. Certain crystals show very interesting properties at the nanoscale. There, we enter the world of nanocrystals, structures that are extremely useful in constructing technological applications at tiny scales.

Perovskites, named after the 19th century Russian mineralogist Lev Perovski, form a particular family of materials that all share the same crystal structure. These have many desirable electronic properties, making them useful for constructing LEDs, TV screens, and lasers. For this reason, perovskites have been studied extensively by physicists in recent years.

When semiconductors – in solar cells, for example – convert the energy of light into electricity, this usually occurs 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 , if the infalling light is energetic enough, further electron-hole pairs can be excited as a result; this process is known as .

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—at most, a little over 33 percent of the solar power gets turned into electrical power. In semiconductor nanocrystals under the carrier multiplication effect, however, a maximum efficiency of up to 44 percent is predicted.

Thus, researchers have sought the carrier multiplication effect in perovskites. Now, de Weerd, Gomez and Gregorkiewicz, along with their collaborators, report this phenomenon. Using spectroscopy methods, the researchers showed that nanocrystals made out of cesium, lead and iodine display carrier multiplication. Moreover, they argue that the efficiency of this effect is higher than reported thus far for any other material; with this finding, the extraordinary properties of perovskites receive a new boost.

De Weerd, who successfully defended her Ph.D. thesis based on this and other research last week, says, "Until now, carrier 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."

Explore further: Shake, rattle, and roll to high efficiency photovoltaics

More information: Chris de Weerd et al. Efficient carrier multiplication in CsPbI3 perovskite nanocrystals, Nature Communications (2018). DOI: 10.1038/s41467-018-06721-0

Related Stories

Shake, rattle, and roll to high efficiency photovoltaics

September 27, 2018

New insight into how a certain class of photovoltaic materials allows efficient conversion of sunlight into electricity could set up these materials to replace traditional silicon solar cells. A study by researchers at Penn ...

Twisting molecule wrings more power from solar cells

November 14, 2017

Inside a solar cell, sunlight excites electrons. But these electrons often don't last long enough to go on to power cell phones or warm homes. In a promising new type of solar cell, the solar-excited electrons have better ...

Recommended for you

After a reset, Сuriosity is operating normally

February 23, 2019

NASA's Curiosity rover is busy making new discoveries on Mars. The rover has been climbing Mount Sharp since 2014 and recently reached a clay region that may offer new clues about the ancient Martian environment's potential ...

Study: With Twitter, race of the messenger matters

February 23, 2019

When NFL player Colin Kaepernick took a knee during the national anthem to protest police brutality and racial injustice, the ensuing debate took traditional and social media by storm. University of Kansas researchers have ...

Solving the jet/cocoon riddle of a gravitational wave event

February 22, 2019

An international research team including astronomers from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has combined radio telescopes from five continents to prove the existence of a narrow stream of material, ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.