[Image above] Chinese manufacturer LONGi currently holds the world record for perovskite–tandem solar cell efficiency, achieving 34.6% efficiency with a two-terminal device. LONGi representatives, pictured above, announced the breakthrough at the 2024 SNEC Expo in Shanghai in June 2024. Credit: LONGi
With silicon-based photovoltaic cells quickly approaching their theoretical maximum energy conversion efficiency of 29%, researchers have turned to perovskite as a way to surpass this inherent limit.
Perovskites are a class of materials with the same crystal structure as calcium titanate (CaTiO3). In addition to having a potential 43% efficiency when used in tandem with silicon, perovskite solar cells can be made into thin films, allowing manufacturers to use high-volume, roll-to-roll fabrication systems that minimize waste and reduce production costs.
Numerous significant advancements in perovskite solar technology took place in 2023, as reported on CTT. Here, we report on some of the latest developments since then.
Tandem solar cells continue to break efficiency records
Since 2023, more work has been done to improve the efficiency of perovskite–silicon tandem solar cells in various configurations.
Tandem solar cells consist of two or more subcells stacked on top of each other, with a perovskite cell on top and a silicon cell on bottom. The top layer collects high-energy light, while the bottom layer captures low-energy light.
As of June 2024, Chinese manufacturer LONGi holds the world record for perovskite–tandem solar cell efficiency, achieving 34.6% efficiency with a two-terminal device. Other organizations have come close. For instance, Taiwan-based Academia Sinica developed a two-terminal perovskite–silicon tandem solar cell with an efficiency of 31.5%.
Four-terminal tandem cells are also reaching new highs. In Japan, Kyoto University spinoff EneCoat Technologies achieved an efficiency of 30.4% for its perovskite–silicon tandem solar cell, which was developed in partnership with Toyota Motor Corporation Ltd. using a proprietary low-temperature deposition process.
In China, scientists built a four-terminal tandem solar cell consisting of perovskite and copper indium gallium. This tandem solar cell achieved an efficiency of 21.26% and a high bifaciality factor of 92.2%. It was created using a stepwise dimethyl sulfoxide solvent annealing strategy, which resulted in a perovskite film with full coverage, larger grains, superior crystallinity, and no lead iodide impurities.
Researchers at Nanjing University in China demonstrated a 0.049 cm2 all-perovskite tandem solar cell with reduced open-circuit voltage losses, achieved by suppressing nonradiative recombination (i.e., energy is released as phonons rather than photons). This feat is made possible by using a 2D perovskite as an intermediate phase on the film surface, which eliminates the need for 2D ligands that can impede carrier transport. The device reached an efficiency of 29.7%.
A team led by Switzerland’s École Polytechnique Fédérale de Lausanne fabricated a tandem cell based on a perovskite top cell and a heterojunction bottom device with double-sided, microtextured surfaces. The bottom cell was fabricated by wet-etching random pyramids, with their height being adjusted by alkaline texturing with no current loss in the cell. An efficiency of 30.22% was achieved.
Perovskite cells have also been combined with organic ones. A team of scientists from China and Germany used this combination to achieve 25.7% efficiency. A novel surface passivator called CyDAI2 was used.
Improving durability and performance
A major limitation of perovskite solar cells is their long-term durability. Perovskite cells begin to deteriorate after just one year of use in contrast to silicon cells, which can last for 25–30 years. Researchers are finding ways to address this challenge by modifying the cell’s chemistry, for example.
Researchers at the University of Surrey and Imperial College London improved both the performance and stability of lead–tin perovskite solar cells by adding an iodine reductant to the cell. This reductant helped prevent device degradation caused by cyanogen formation, which allowed the cells to achieve 23.2% efficiency and a service life extended by 66%.
The University of Surrey also found alumina nanoparticles significantly enhanced the lifespan and stability of perovskite devices, maintaining high performance for more than two months (1,530 hours) compared to just 160 hours without the nanoparticles. Surrey is building a 12.5-MW solar farm to test these panels in real-world conditions.
Another solution to the degradation problem is to replace the type of perovskite used in the solar cell. Researchers at the Australian Centre for Advanced Photovoltaics showed that chalcogenide perovskites based on BaZrS3 are more durable than halide ones. The material is also nontoxic. A tandem solar cell combining chalcogenide perovskite and silicon improved efficiency by 38%.
Modifications to the processing parameters can also help improve cell stability and performance. Chinese and French scientists combined a slot-die coating strategy with pyrrodiazole additives in the perovskite precursor solution to simultaneously immobilize lead and formamidinium iodides to achieve inverted perovskite solar modules. The 10 cm × 10 cm modules achieved a certified efficiency of 20.3%, and stability was good with a 94% efficiency rating after exposure to direct light for 1,000 hours at 65% humidity.
Indian Institute of Technology researchers introduced a novel NiO/Ag/NiO transparent electrode using a low-energy physical vapor deposition technique. The electrode has exceptionally low electrical resistance and high visible light transmittance, significantly enhancing solar cell performance. Bifacial solar cells incorporating this electrode maintained 80% of their initial efficiency for more than 1,000 hours without any protective encapsulation.
Because conventional solvents such as C3H7NO pose environmental hazards, Nanjing University researchers developed a green solvent for tandem solar cells. Based on dimethyl sulfoxide, acetonitrile and ethyl alcohol, the solvent can be used to fabricate both wide-gap and narrow-gap cells. Solar modules made with 20.25 cm2 all-perovskite cells achieved an efficiency of 23.8%.
Molecules called ligands also affect perovskite solar cell stability, and researchers are looking for ones that can best help passivate surface defects and enhance crystal orientation. For instance, Northwestern University researchers replaced the ammonium-based ligand with an amidinium one because it is 10 times more resilient. A 26.3% efficiency was achieved in inverted solar cells, which was retained at 90% or more for 1,100 hours at 85°C.
For all-inorganic perovskite cells, other Chinese researchers used a stabilizing ligand, para-toluenesulfonyl hydrazide (PTSH), to achieve an efficiency of up to 22%. This ligand helps suppress degradation reactions and is also compatible with spin-coating. A two-terminal tandem structure maintained 80% of the initial efficiency even after 1,500 hours of operation at 65ºC and 800 hours at 85ºC.
An international team of researchers led by King Abdullah University of Science and Technology in Saudi Arabia developed a 3D/2D perovskite solar cell based on a meta-amidinopyridine ligand that improved ferroelectric properties and passivation effects at the cell’s 3D/2D interface without deteriorating charge transport. The solar cell achieved a maximum efficiency of 26.05%.
To evaluate performance, it is also important to test devices under real-life conditions. Researchers from Belgium and the University of Cyprus completed outdoor stability tests of metal halide perovskite solar minimodules (4 cm2). Results showed the modules’ performance loss rates ranged between 7–8% per month. The most durable minimodule maintained 78% of its initial efficiency after one year. Further field trials are underway in diverse climate zones around the world.
Perovskite solar cells reach the market
As researchers continue to improve efficiency, companies are announcing commercialization of their products. In September 2024, U.K.-based Oxford PV shipped their tandem 72-cell panels to the United States for a utility-scale installation. The modules have 24.5% efficiency, and Oxford PV plans to increase production to gigawatt scale in the future.
Korea-based Qcells reported a new world record in December 2024 for large-scale solar panels, reaching 28.6% efficiency on a full-area M10-sized (330.56 cm2 or 51 in.2) tandem solar cell. This cell can be scaled for mass manufacturing.
In March 2025 China-based UtmoLight announced it reached 18.1% efficiency with its 0.72-m² perovskite photovoltaic modules, claiming a new global efficiency record for modules of this size. Its 150-MW pilot line has supplied perovskite modules to commercial projects across several Chinese provinces. Another Chinese company JinkoSolar claims a 33.84% efficiency for a perovskite–silicon tandem solar cell based on n-type wafers.
Queen Mary University of London and Power Roll are commercializing perovskite solar film. Power Roll combines microgrooves and vacuum forming to produce perovskite films less than a millimeter in thickness.
U.S. startup BlueDot Photonics developed a perovskite-doped manufacturing system, which enables a 16% increase in the solar conversion efficiency of silicon solar panels by applying a perovskite thin film, leading to a 10% drop in the cost of solar power.
For the consumer market, China-based Anker claims the perovskite cells used in its Solix Solar Beach Umbrella have 30% better performance than silicon ones in bright light and double the efficiency in low light. Up to 100 W of total output from XT-60 and USB-C connections is possible.
Some countries have made major commitments to commercializing perovskite technology. Under Japan’s revised energy plan, the country has prioritized perovskite cells for development, generating 20 gigawatts of electricity by fiscal 2040. Japan is the second-largest iodine producer in the world, a necessary ingredient in the manufacturing of perovskite solar cells.
Japanese company Sekisui Chemical Co. is developing advanced perovskite solar cell modules for future markets by 2030, with predictions that costs will fall to 14 cents per watt (10 yen per watt) by 2040.
A Japanese consortium is also testing 80 flexible panels measuring 30 cm x 1 m each at Osanbashi Pier in Yokohama City, which features windy and salt-air conditions. The modules have an efficiency of 10% and are manufactured in a roll-to-roll process with indium tin oxide on plastic films for roof installations and other applications.
A European consortium is developing miniaturized in-space propulsion devices that operate without propellants. They are based on electrodynamic tether technology integrating perovskite–copper indium gallium (di)selenide tandem solar cells. Potential benefits include a major reduction in satellite costs while significantly increasing the proportion of usable satellite mass, freeing up space for scientific experiments, antennas, or cameras.
Kesterite: The potential new kid on the block
As progress continues with perovskite, other materials are coming on the scene. One such material is kesterite (Cu2ZnSnS4), a wide-bandgap material that may allow for more efficient light absorption. Kesterite also has the advantages of long-term performance, low manufacturing costs (inexpensive ingredients), and environmental friendliness (nontoxic).
The University of New South Wales recently achieved an efficiency of 13.2% for kesterite solar cells by using hydrogen annealing to reduce the impacts of carrier recombination. The researchers hope to increase efficiency above 15%.
Of course, this efficiency is far below that of current perovskite and silicon solar cells. It remains to be seen if kesterite can reach these higher levels and how it will impact the solar energy market.
