Rice University engineers have improved the efficiency of atomically thin solar cells made from semiconductor perovskites. Usually progress in this area is measured in fractions of a percent.

New work from the George R. Brown Rice School of Engineering found that sunlight shrinks the space between atomic layers in 2D perovskites enough to increase the photoelectric efficiency of the material by up to 18%.

Over 10 years, the effectiveness of perovskites has increased dramatically from about 3% to more than 25%. It took other semiconductors about 60 years to achieve this.

Adya Mohite, Fellow, George R. Brown Rice School of Engineering

Perovskites are crystals that have a pseudo-cubic (broken cubic) structure. Their potential has been known for many years: they are good at converting sunlight into energy. But crystals are unstable, so sunlight and moisture destroy them. The authors note that 2D perovskites are extremely stable, but not efficient enough to be widely used.

So researchers were looking for a way to make them both stable and effective. During their work, they found that in some two-dimensional perovskites, sunlight shrinks the space between atoms so that their ability to carry current improves.

The authors tried to place a layer of organic cations between the iodide on top and the lead on the bottom: this increased the interaction between the layers. Scientists conducted computer simulations, which confirmed the effectiveness and efficiency of the new approach.

Both results showed that the material shrank 0.4% in length and about 1% in volume after 10 minutes under the solar simulator. This shortening of the distance results in a significant increase in the electron flux.

At the same time, the nature of the grating made the material less susceptible to degradation, even at temperatures up to 80 ° C. The researchers also found that the grating quickly returned to its normal state as soon as the lights went out.