Researchers Develop Perovskite Solar Cells with ~93% Bifaciality

NREL researchers calculated the efficiency from reflected light hitting the back of the device


A team of researchers at the  U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) has claimed to achieve 91%-93% of bifaciality on a newly developed bifacial perovskite solar cell.

The researchers designed a perovskite bifacial solar cell with a modified thickness and achieved efficiencies under illumination from both sides, which were very close together.

They utilized optical and electrical simulations to determine the necessary thickness to be constructed into the cell.

The perovskite layer on the front of the bifacial solar cell had to be thick enough to absorb most of the photons from a certain part of the solar spectrum but not too thick that it would block them. The team also determined the ideal thickness of the rear electrode to minimize resistive loss.

The simulations guided the team to design the bifacial cell with an accurate thickness of 850 nanometers.

The researchers placed the cell between two solar simulators to evaluate the efficiency gained through bifacial illumination. The direct light was aimed at the front side, while the rear received the reflected light.

The efficiency of the perovskite cell increased as the ratio of the reflected light to the front illumination increased.

The researchers claimed that the lab-measured efficiency of the front illumination crossed 23%, and from the back illumination, the efficiency was about 91%-93% of the front side.

The study “Highly efficient bifacial single-junction perovskite solar cells” was published in the journal Joule.

In the past, bifacial perovskite solar cell research developed devices not competent enough compared to monofacial cells with a record efficiency of ~26%.

The dual nature of bifacial solar cells enables them to capture direct sunlight on the front and reflected sunlight on the back, allowing them to outperform their monofacial counterparts.

Bifacial perovskite solar modules are known to cost more to manufacture than the widely used monofacial modules. However, the researchers estimate that bifacial modules could become better financial investments because of the 10-20% higher power generation.

The U.S. Department of Energy Solar Energy Technologies Office funded the research.

Recently another team of researchers at NREL and Northern Illinois University developed a layer made of nickel-doped graphite combined with a bismuth-indium alloy as a cost-effective alternative to the gold layer used on perovskite solar cells.

In March this year, NREL devised a new way to produce perovskite solar cells that could speed its commercialization. After 1,200 hours of continuous operation, the team created a high-efficiency solar cell that maintained over 90% of its initial efficiency.

(Image Credit: NREL researchers designed bifacial perovskite solar cell)