An international team of researchers, led by the Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, have developed a perovskite solar cell that features a 2D/3D heterojunction architecture with a power conversion efficiency of 25.32%  (certified 25.04%) under standard illumination.

The research, published in Advanced Materials, tested the perovskite solar cell for its stability after 2,000 hours of operation and observed that the cell retained a remarkable 90% of its initial efficiency.

The scientists used the newly developed cell technology to build a mini-module, showcasing its versatility and adaptability to larger-scale applications.

The mini-module reached an efficiency of 21.39%, an open-circuit voltage of 9.416 V, and a fill factor of 80.3%. The researchers believe that with further optimization, these modules have the potential to achieve an efficiency of approximately 23%.

The innovation could hold immense promise for various photovoltaic (PV) applications, including conventional PV systems, vehicle-integrated solar (VIPV), and building-integrated photovoltaics (BIPV).

The team said the key to the success of this novel solar cell lies in its unique 2D/3D heterojunction architecture. The design incorporates a 2D perovskite layer positioned at the interface between the perovskite and the hole transport layer.

The strategic placement significantly enhances the transport and extraction of charge carriers while simultaneously suppressing ion migration, thus optimizing the cell’s overall performance.

One of the notable characteristics of cells utilizing this architecture is their ability to exhibit large exciton binding energies. Additionally, they tend to be more stable than conventional 3D devices, primarily due to the protection offered by the organic ligands.

Furthermore, the interlaminar molecules in the 2D perovskites are crucial in saturating the 3D perovskite surface during fabrication. This action effectively reduces surface defects, forming a potential energy offset for field-effect passivation.

The research team employed a designed composition of materials to create this solar cell, which includes a tin oxide (FTO) substrate, an electron transport layer made of titanium oxide (TiO2) and tin (IV) oxide (SnO2), a 3D perovskite layer, a 2D perovskite layer, a spiro-OMeTAD hole transport layer, and a gold (Au) metal contact.

The fabrication process for the 2D perovskite absorber involved using a precursor called n-butylammonium iodide (BAI). This precursor was instrumental in increasing the activation energy of the layer to 0.52 eV.

The researchers attributed this increase to the larger migration energy resulting from the substantial distance between the interlayer spacings of the 2D perovskite.

Commercial production of these modules is expected within the next three years, with estimated cell costs of $0.02/kWh and an energy payback time of just six months.

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

Also, recently researchers from King Abdullah University of Science and Technology (KAUST), in a significant discovery, claimed to surpass the efficiency milestone of 30% for tandem silicon-perovskite solar cells.