Stability

Scientists at the Chinese Academy of Sciences (CAS), Xuancheng Kaisheng New Energy Technology Company and Tianjin Institute of Power Sources have found a way to make flexible tandem solar cells more efficient and durable by enhancing the adhesion of top layers to the bottom layers of the cell.

Copper indium gallium selenide (CIGS) is a commercial semiconductor known for its outstanding adjustable bandgap, strong light absorption, low-temperature sensitivity, and superior operational stability, making it a promising candidate for bottom-cell use in next-generation tandem solar cells. Flexible perovskite/CIGS tandem solar cells combine a top layer of perovskite with a bottom layer of CIGS. This tandem cell holds great potential for lightweight, high-efficiency applications in the photovoltaic field but the rough surface of CIGS makes it difficult to produce high-quality perovskite top cells on top, which limits the commercial prospects of these tandem cells.

Researchers from Ulsan National Institute of Science and Technology (UNIST), Gyeongsang National University (GNU) and University of Ulsan explain that in spiro-OMeTAD-based hole-transporting layer (HTL) protocols, 4-tert-butylpyridine (tBP) is an indispensable component; however, its inclusion leads to substantial detrimental effects, hindering thermal stability. 

Recently, the team developed a tBP-free spiro-OMeTAD approach by substituting ethylene carbonate (EC) electrolyte for tBP. The electronegative carbonyl functionality led to the formation of a solvation complex with Li⁺ ions, addressing the solubility concern of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in chlorobenzene even without tBP. 

Researchers from Daegu Gyeongbuk Institute of Science and Technology (DGIST), Lawrence Berkeley National Laboratory, University of California and Pohang University of Science and Technology (POSTECH) have observed and identified the water-induced degradation mechanism of perovskite in real time at the atomic scale. 

Image from: Matter

This recent study presents key strategies for enhancing the stability of perovskite materials and could accelerate their commercialization. 

NiOx shows promise for large-area perovskite technologies thanks to excellent semiconductor properties, ease of large-area deposition, and tunable optoelectronic characteristics. However, NiOx-based perovskite solar cells (PSCs) tend to be limited by interfacial photocatalytic chemical reactions and energy level mismatch. Thus, phosphate-based self-assembled monolayers (SAMs) have been developed for delicate interfacial modification but these suffer from severe issues such as self-aggregation and high cost.

Image from: Journal of Energy Chemistry

Researchers from China's Fudan University and Shanghai Geoharbour Construction Group have addressed this issue by developing a low-cost carboxylate-based SAM (pyrenebutyric acid, PyBA) to modify NiOx, achieving an improved surface chemical environment and interfacial properties, such as an increased Ni³⁺/Ni²⁺ ratio, a reduced proportion of high-valence Ni^≥3+, and better-aligned hole transport interface energy level. 

The inhomogeneity of hole-selective self-assembled molecular layers (SAMLs) often arises from the insufficient bonding between anchors and metal oxides, particularly on textured silicon surfaces when fabricating monolithic perovskite/silicon tandem solar cells (P/S-TSCs) and the hydrophobic carbazole complicates the fabrication of high-quality perovskite films. 

To address this, researchers from the Chinese Academy of Sciences (CAS), Advanced Solar Technology Institute of Xuancheng and North Minzu University have developed a bidentate-anchored superwetting aromatic SAM based on an upside-down carbazole core as a hole-selective layer (HSL), denoted as ((9H-carbazole-3,6-diyl)bis(4,1-phenylene))bis(phosphonic acid) (2PhPA-CzH). 

Researchers from EPFL, National University of Singapore and Nanjing University of Aeronautics and Astronautics have used lattice strain to lock in rubidium, which helped cut energy loss and push perovskite solar cells to 93.5% of their theoretical efficiency limit. By utilizing the controlled distortion in the atomic structure, this approach not only stabilized the wide-bandgap (WBG) perovskite but also improved efficiency by cutting non-radiative recombination, a major cause of energy loss.

Known for absorbing high-energy light while letting lower-energy light pass, wide-bandgap materials offer major gains in energy capture but are prone to phase segregation, a phenomenon that takes place when different components of the material separate over time, leading to a decline in performance. While adding rubidium to help stabilize the semiconductors has been proposed as a potential way to address the issue, the element often forms unwanted secondary phases, which limits its ability to strengthen the perovskite structure. However, the scientists fine-tuned the material’s composition in a process that involved rapid heating followed by controlled cooling. This created lattice strain, that prevented rubidium from forming unwanted secondary phases and kept it integrated within the crystal structure.

Researchers from the University of Potsdam, TU Berlin, HZB, BHT Berlin and Salerno University have reported halide perovskite photovoltaics (PV) fabricated on regolith-based moonglass that could be produced on the Moon, thereby saving 99% of material transport weight. Regolith is a silicate-rich material that covers the Moon’s surface. 

Image from: Device

This method reportedly enables effective specific power ratios, over 22–50 W/g, a factor of 20–100 higher compared to traditional space PV solutions, while not compromising radiation shielding, reliability, and mechanical stability as was the case until now. 

A research team from Ulsan National Institute of Science and Technology (UNIST), University of New South Wales, University of Surrey and 
Korea Research Institute of Chemical Technology have developed an interlayer that leverages the specificity of organic cations on the surface of perovskite solar cells (PSCs), simultaneously achieving high-efficiency and durability.

Credit: Joule (2025)

PSCs generate electrical energy by transferring charge carriers created when the light-absorbing material absorbs sunlight to the electrodes. Minimizing defects in this light-absorbing layer is essential for effectively delivering charges to the electrodes and enhancing cell efficiency. Previously, research focused on the use of single organic cations, which posed challenges such as structural collapse of the thin films due to the migration of individual cations and energy level misalignment. Energy levels serve as a "staircase" pathway for charge movement; if the interlayer energy levels are misaligned, charge losses can occur, leading to reduced efficiency.

Researchers from the Adolphe Merkle Institute/ University of Fribourg, Université Grenoble Alpes, Forschungsschwerpunkt Organic Electronics & Photovoltaics, Pusan National University, University of Pavia, University of Tübingen, EPFL and Universidad de Antioquia UdeA have developed a novel light-responsive material that enhances the performance and longevity of perovskite solar cells. This innovation could improve the stability of perovskite solar technology and prevent rapid degradation under real-world conditions.

The key innovation is a photochromic compound called SINO, which changes its properties when exposed to light. When integrated into perovskite solar cells, SINO acts as a dynamic protective layer that adapts to changing conditions during operation. This material transforms between two states in response to sunlight, helping to suppress ion migration within the perovskite and facilitate charge extraction.

Researchers from the University of Sydney and Shanghai Jiao Tong University have combined first-principles calculations and machine learning molecular dynamics to examine the interplay between perovskite octahedral lattice dynamics and energy barrier associated with ion migration. 

Image from: Science Advances

The team reported suppressed ion migration in halide perovskites specifically at the B-site, opening the door to cell stabilization by minimizing energy loss and improving performance reliability.