Perovskite Solar

Researchers at Sophia University in Tokyo, led by Professor Yuko Takeoka of the Faculty of Science and Technology's Department of Materials and Life Sciences, together with contributing researchers from the National Institute for Materials Science (NIMS), have developed a multifunctional molecular passivation strategy for tin-based perovskite solar cells that improves both efficiency and long-term durability. Adding a small heteroatom molecule, 2-aminobenzothiazole (2-ABZ), to quasi-two-dimensional Ruddlesden-Popper tin perovskite devices raised power conversion efficiency to 9.07%, up from 6.60% for untreated control devices, while improving how well the cells hold up over time.

Tin-based perovskites are widely seen as the leading lead-free alternative to conventional lead halide perovskite solar cells, offering a route around the toxicity concerns associated with lead, but they have historically lagged behind on both efficiency and stability, limiting their commercial viability. The Sophia University and NIMS team addressed this by incorporating 2-ABZ, a molecule containing nitrogen, carbon, sulfur, and hydrogen, into the perovskite layer as what the researchers describe as a multifunctional molecular stabilizer. Rather than targeting a single failure mode, 2-ABZ acts across the device architecture: it regulates crystallization, reduces trap formation, prevents ion migration, inhibits tin oxidation, and improves interfacial energy alignment.

Researchers at the University of Electro-Communications (UEC) in Tokyo and Madan Mohan Malviya University of Technology (MMMUT) in India have developed a new solvent and additive system that enables solution-processed, lead-free germanium-tin (Ge-Sn, 1:1) perovskite solar cells, reaching 4.56% efficiency, which the team describes as the highest performance achieved with any solution-based method for this composition to date.

Germanium and tin are both being explored as isoelectronic, lower-toxicity alternatives to lead in halide perovskite solar cells, but Ge-Sn alloyed perovskites have been difficult to process from solution: the team found that dimethyl sulfoxide (DMSO), a solvent commonly used in perovskite fabrication, reacts too rapidly with the germanium precursor GeI₂, preventing the formation of clean, pure-phase films. To get around this, the researchers developed a DMSO-free solvent system based on a mixture of N,N-dimethylformamide, N,N′-dimethylpropyleneurea, and 4-tert-butylpyridine, which suppresses that unwanted reactivity and allows Ge-rich perovskite films to be wet-coated while forming a pure-phase Ge-Sn (1:1) structure, confirmed by X-ray diffraction.

Hanwha Solutions, parent company of solar manufacturer Qcells, and Hanwha Systems, its sister company specializing in defense and satellite systems, recently signed a joint development agreement to develop high-efficiency perovskite-silicon tandem solar cells for satellite power systems, marking Hanwha's entry into the space solar power market. Hanwha Systems is investing 30 billion won (about $20 million) in a research program running from 2026 through 2028.

Under the agreement, Hanwha Solutions will lead research through 2028 focused on improving high-efficiency cell design and performance and verifying reliability under space conditions, developing power solutions optimized for very low Earth orbit (VLEO), where lightweight structures and resilience to a demanding orbital environment are critical. The companies plan to conduct an in-orbit demonstration in 2028 to validate the technology under real space conditions, with a commercialization pathway aimed at integrating the tandem cells into Hanwha Systems' planned constellation of 64 very-low-Earth-orbit synthetic aperture radar (SAR) satellites, capable of resolving ground objects as small as 15 centimeters, with deployment targeted to begin in 2029. Beyond VLEO, the companies say they intend to further develop the technology for use across other orbital environments, including low Earth orbit (LEO) and medium Earth orbit (MEO).

Researchers at Nanjing University and the Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, have developed a new near-infrared-absorbing acceptor molecule that pushes two-terminal perovskite-organic tandem solar cells to a power conversion efficiency of 27.35%, certified at 26.88%, alongside improved operational stability.

Perovskite-organic tandem solar cells have drawn growing interest because both the perovskite and organic layers can be processed from solution at room temperature and remain flexible, opening the door to vehicle-integrated and building-integrated photovoltaics, while the wide-band-gap perovskite layer's filtering of ultraviolet light is expected to improve operational stability relative to other tandem architectures. Even so, certified efficiencies for this tandem type have lagged behind other perovskite-based tandems such as perovskite-silicon and all-perovskite designs, largely because the low-band-gap organic subcell generates less photocurrent than the wide-band-gap perovskite subcell above it. That mismatch stems from heavy overlap between the two subcells' external quantum efficiency (EQE) spectra near the perovskite's band-gap edge, which suppresses the organic subcell's usable photocurrent once it's stacked underneath a perovskite layer.

Researchers at Hebei University of Technology, Jiaxing Daze Photoenergy Co., Jiaxing Nanhu University, Taizhou University, Chimie ParisTech (CNRS, PSL Research University, France), Tianjin University, Harbin Institute of Technology (Shenzhen), Nankai University, and the National University of Defense Technology, have developed a molecular additive strategy that boosts inverted perovskite solar cells to a certified stabilized efficiency of 27.10% (peak 27.39%) while enabling large-area bifacial modules that exceed 22% efficiency on both sides and retain 99.6% of their output after 5,000 hours of continuous illumination.

Perovskite solar cells are now efficient enough that remaining performance losses are governed less by light harvesting and more by small defects that form during rapid film crystallization and concentrate at surfaces, grain boundaries, and buried interfaces. Molecular additives are a common way to passivate these defects, but the field has run into a persistent trade-off: molecules that bind strongly to defects can also pack too densely or create insulating interfacial layers that block charge transport, while additives designed for easy charge transport often bind too weakly to be effective passivators.

Researchers at the University of Wisconsin–Madison, the National Laboratory of the Rockies, the University of Toledo, and the University of Colorado Boulder, have designed a tin-based perovskite with built-in protection against air and moisture, addressing a major obstacle to achieving practical lead-free perovskite photovoltaics. Devices built with the new material reached 16.2% power conversion efficiency, among the best reported for tin perovskite solar cells, while showing markedly improved durability.

Tin-based perovskites are considered the leading lead-free alternative thanks to favorable light-absorbing and electronic properties, but they are especially vulnerable to oxygen and moisture, which rapidly degrade the material and its performance, limiting practical deployment. To address this, the team examined how the organic components of these hybrid materials assemble and designed new tin perovskites intended to impede damage from oxygen and water. They synthesized and compared a family of closely related organic cations substituted with different halogen atoms (fluorine, chlorine, and bromine), and found that the chlorinated version, 4-chloro-phenethylammonium (4ClPEA), packed most tightly into the crystal structure.

Researchers at the Ulsan National Institute of Science and Technology (UNIST), led by corresponding authors Professor Changduk Yang, Professor Seung-Jae Shin and Professor Myoung Hoon Song, have developed a self-assembled monolayer (SAM) hole-selective contact for inverted perovskite solar cells that keeps working through repeated thermal cycling between −100°C and +100°C. The material, named LY-m, isolates the effect of molecular linker position on interfacial packing and pushed cell efficiency to 26.39% (certified 26.37%) with a record-high open-circuit voltage of 1.231 V.

In inverted (p-i-n) perovskite solar cells, SAMs form a molecule-thin hole-selective layer between the transparent electrode (ITO) and the perovskite absorber, and their performance is highly sensitive to incomplete surface coverage, molecular aggregation, and interfacial heterogeneity, particularly under heat and large temperature swings. While SAM chemistry has been widely explored, how the molecular topology of the linker itself governs packing and device durability had remained poorly understood. To isolate that variable, the UNIST team synthesized three isomeric SAMs, LY-ortho (LY-o), LY-meta (LY-m), and LY-para (LY-p), that share an identical carbazole head group and differ only in where the linker attaches to the ring.

FAW's Hongqi brand has built what it calls the industry's first perovskite photovoltaic sunroof prototype, integrating the material directly onto curved automotive safety glass rather than using conventional crystalline silicon. Fitted to the Hongqi EHS7 electric SUV, marketed in China as the Hongqi Tiangong 08, the sunroof can generate up to 300 W of power under strong sunlight and around 400 kWh over a year. The technology remains at the prototype stage, with no mass-production timeline disclosed.

Hongqi EHS7, which is marketed in China with the name Tiangong 08. Photo: CarNewsChina

The EHS7/Tiangong 08 is a five-passenger SUV measuring 4,925 mm long, 1,950 mm wide, and 1,680 mm tall, with 253 kW (339 hp) of peak power and a WLTP-rated range of 475 km. Hongqi said it passed over crystalline silicon for the sunroof because the material is fragile and offers lower efficiency for the application, choosing perovskite instead for its light weight, thinness, flexibility, high light-to-electricity conversion efficiency, tunable coloring, and lower cost. Integration wasn't without difficulty: perovskite's known vulnerability to water, oxygen, and ultraviolet exposure, combined with the curved geometry of the sunroof glass, reportedly posed challenges for the development team.

Researchers at the University of Freiburg's Early-Career Research Group on Optoelectronic Thin-Film Materials (INATECH) and the Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE), together with Martin Luther University Halle, Universidad Pablo de Olavide, and the King Abdullah University of Science and Technology (KAUST), have fabricated what is described as 'the world's first perovskite-silicon tandem solar cell manufactured entirely without solvents'. 

The device reached a champion power conversion efficiency (PCE) of 27.3%, stabilized at 27.0%, and retained 97.06% of its initial efficiency after 6,800 hours of dark storage in a nitrogen atmosphere.

The U.S. Department of Energy's Office of Critical Minerals and Energy Innovation has announced a $12 million funding opportunity to accelerate technical innovation and expand domestic manufacturing for space-grade solar panels, through the Space Photovoltaics (PV) Research and Development Partnership Intermediary Agreement (PIA). While the program covers space PV broadly, both of its topic areas specifically call for perovskite-based projects, according to program representatives.

“The next frontier for solar PV power generation is in space,” said Assistant Secretary of Energy Audrey Robertson. “As demand for space-grade PV skyrockets, this investment will establish American leadership in next-generation, space-based PV, bolster our national security, and enhance our economic competitiveness.”