Tech Insights

Researchers Reimagine Solar With Bifacial Perovskite Breakthrough

May 31, 2023 by Jake Hertz

The research demonstrates the best-performing bifacial perovskite solar cells yet.

Solar is the most popular and effective among the many forms of renewable energy. However, it is widely noted that the technology has a way to go before its widespread adoption.

Perovskite solar cell

Perovskite solar cell. Image used courtesy of Adobe Stock

Perovskite solar cells are a promising technology for improving solar cell efficiency. Unfortunately, perovskite cells are in their infancy and have significant development before replacing conventional solar technology. 

Researchers from the University of North Carolina (UNC) Chapel Hill recently made strides toward developing viable bifacial perovskite solar cells. 


Perovskite Solar Cells

For researchers seeking to create higher efficiency solar cells than what currently exists, perovskite solar cells are an exciting emerging technology.

Perovskite cells refer to photovoltaic devices that use perovskite materials as the light-harvesting layer. Perovskite materials, in turn, have the same crystal structure as the mineral calcium titanium oxide, the first perovskite material discovered. Uniquely, perovskite materials offer some features making them particularly well-suited for use in solar cells.


Schematic of a perovskite solar cell

Schematic of a perovskite solar cell. Image used courtesy of OIST


For example, perovskite materials offer exceptional broad-spectrum absorption, meaning they can absorb a wide spectrum of light wavelengths. Solar cells made from perovskite materials can use a larger portion of the solar spectrum than traditional cells, allowing them to convert more incident light into usable power.

Additionally, perovskite materials offer efficient charge carrier generation. When these materials absorb photons, large numbers of electron-hole pairs are created by the interaction of light with the material. 

Together, these features result in perovskite solar cells having a much higher theoretical efficiency than traditional solar cells.


UNC Research 

The holy grail in the world of perovskite cells is the bifacial perovskite cell. Unlike traditional cells, which offer light absorption on one face of the panel, a bifacial solution equips cells on both faces. Here, the outward face absorbs light directly from the sun while the backward face absorbs albedo light (i.e., light reflected off nearby objects). Thanks to this second face, a bifacial perovskite cell can potentially produce even greater energy than a standard perovskite cell.

In a paper in Nature Energy, the researchers describe the creation of a high-energy-yield bifacial perovskite cell with a long operational lifetime.


UNC researchers with their perovskite cell

UNC researchers with their perovskite cell. Image used courtesy of UNC


In their study, the researchers designed a bifacial perovskite cell based on individual sub-cells connected via indium tin oxide (ITO) interconnects. The design employed some unique design concepts to improve the cell performance, including adding a tris(pentafluorophenyl)borane (TPFB) additive to the hole transport layer to avoid moisture-related damages and introducing nanoparticles into the perovskite material to scatter incident sunlight.

With these design features, the team built a small perovskite cell with a power dentistry of 26.4 mW/cm^2. Additionally, the team built a bifacial minimodule that reached a power generation of 23 mW/cm^2 from direct sunlight and albedo light. Most importantly, the bifacial minimodule showed a front efficiency of over 20%, a bifaciality of 74.3%, and retained 97% of its initial efficiency after 6000 hours of direct light exposure.


Improving Solar

With the new study from UNC-Chapel Hill, the researchers claim that they’ve developed a bifacial perovskite cell that is significantly better than previously demonstrated solutions. If true, they’ve likely made a big step toward developing commercially-competitive perovskite cells and, eventually, toward a more sustainable future.