Phosphotene nanoribbons (PNRs) are ribbon-like chains of the two-dimensional material phosphorus, similar to graphene, made up of atomic layers one atom thick.PNRs were first produced in 2019, and hundreds of theoretical studies have predicted how their performance could enhance a variety of devices, including batteries, biomedical sensors, and quantum computers.
However, so far, these predicted excitation properties have not been confirmed in actual devices. Now, for the first time, a team led by researchers from Imperial College London and University College London has used PNRs to significantly improve the efficiency of a device – a new type of solar cell – proving that this "wonder material" may live up to its hype.
The details are published today in the Journal of the American Chemical Society.
Lead researcher Dr. Thomas MacDonald, from imperial College's Department of Chemistry and Centre for Machinable Electronics, said: "Hundreds of theoretical studies have foreseen the exciting properties of PNRs, but there have been no published reports demonstrating these properties, or their translation into improved device performance."
"We are therefore pleased not only to provide the first experimental evidence of PNRs as a promising route for high-performance solar cells but also to demonstrate the versatility of this novel nanomaterial for use in next-generation optoelectronic devices."
The team integrated PNRs into solar cells made from perovskite. Perovskites are a new class of materials that scientists can easily change the way they interact with light to suit a range of applications.
Unlike traditional silicon-based solar cells, perovskite solar cells can be made from a liquid solution, making low-cost printing a flexible film. New nanomaterials, such as PNRs, can simply be printed as an additional layer to improve device functionality and efficiency.
By introducing PNRs, the team was able to produce perovskite solar cells with an efficiency of over 21%, comparable to traditional silicon solar cells. They were also able to verify experimentally how PNR achieves this efficiency gain.
They showed that PNRs increased "hole mobility"."Holes" are the opposite partners of electrons in electron transport, so improving their mobility (a measure of how fast they move through the material) helps the current move more efficiently between the layers of the device.
Experimental verification of the power of PNRs will help researchers create new design rules for optoelectronic devices (devices that emit or detect light), the team said.
Dr. McDonald said: "Our results show that the functional electronic nature of PNRs can indeed translate into improved function. This highlights the real importance and usefulness of this newly discovered nanomaterial and sets the benchmark for PNR-based optoelectronic devices."
Further studies using PNRs in devices will allow researchers to discover additional mechanisms to improve performance. The team will also explore how to improve the unique electronic properties of the material by modifying the surface of the nanoribbon.
