The National Renewable Energy Laboratory (NREL) has devised a new way to produce perovskite solar cells that could speed its commercialization.

Different layers are typically added sequentially to a conductive glass substrate to create perovskite solar cells, requiring multiple coatings.

However, the new method developed eliminates or merges some of these steps, simplifying the manufacturing process and potentially reducing costs.

After 1,200 hours of continuous operation, the team created a high-efficiency solar cell that maintained over 90% of its initial efficiency.

Perovskite solar cells comprise a light-absorbing perovskite layer and adjacent layers that extract opposite charges when light is absorbed. The hole-transport layer (HTL) is one such layer that pulls positive charges.

While perovskites can be made without an HTL, the efficiency of these devices is lower than that of full perovskite solar cells.

Xiaopeng Zheng, a postdoctoral researcher at NREL’s Chemistry and Nanoscience Center, explains how a one-step solution-coating process enabled the formation of two distinct layers – the HTL and perovskite absorber – in a single coating step.

This process eliminates the need for a separate hole-transport layer and instead creates a self-assembled monolayer that serves as a hole-selective contact while the perovskite crystalizes.

According to Zheng, the simplified process of producing the HTL and perovskite simultaneously reduces the number of coating and heating steps while eliminating the need for expensive HTL materials.

“It is challenging to uniformly manufacture a thin HTL layer using the scalable solution method, and this may also be a barrier to commercialization…our approach could also avoid this problem,” Zheng said.

He estimates that eliminating the previous steps required to create the HTL and heating it could reduce the solution-processing time by a third.

“Even if we didn’t save much time here, it brings about the notion that the manufacturing process could be re-evaluated with this new concept in mind,” said Joseph Luther, a corresponding author of the paper and senior research fellow within the Materials, Chemical, and Computational Science Directorate at NREL.

Zheng said that although the initial discovery of the procedure was made at NREL, the co-authors from other institutions could replicate and strengthen the findings.

The Center for Hybrid Organic-Inorganic Semiconductors for Energy provided support in understanding the different layers crystallize.

Recently, researchers at Helmholtz-Zentrum Berlin found that solar cells made of metal halide perovskites achieve high efficiencies and can be produced from liquid inks with little energy input.

In the same month, Italy-based renewable energy company Enel Green Power, researchers at the National Solar Energy Institute, and the French Alternative Energies and Atomic Energy Commission claimed to have achieved a power conversion efficiency of 26.5% for a 2-terminal tandem perovskite solar cell.