Efficiency

A team of researchers, led by the Chinese Academy of Sciences (CAS), has developed a generalizable strategy to control crystallization kinetics in all-perovskite tandem solar cells, enabling certified power conversion efficiencies of 30.3% in rigid devices and 28.0% in flexible configurations.

Synchronized crystallization drives efficient rigid and flexible perovskite tandems. Image credit: NIMTE

All-perovskite tandems can enable high efficiency and compatibility with low-temperature solution processing. However, their performance has been consistently limited by asynchronous crystallization in multicomponent perovskite systems. This effect arises from mismatched coordination chemistry and crystallization rates among mixed halide systems and Pb²⁺/Sn²⁺ cations, leading to vertical compositional gradients, structural inhomogeneity, and elevated non-radiative recombination losses.

Researchers from China Jiliang University, Wuhan University, Hangzhou Dianzi University and Hubei Normal University have introduced a bilayer interface engineering strategy that induces a vertically oriented 1D perovskite capping layer on top of a 3D perovskite absorber. 

This architecture targets 1D/3D heterostructure perovskite solar cells, which are already known for their exceptional stability but usually suffer from horizontally aligned or disordered 1D phases that hinder carrier transport along the device thickness. By enforcing vertical alignment of the 1D phase, the new design directly improves charge extraction along the preferred transport direction.

Researchers at Nanjing University, the Australian National University, North China Electric Power University and Beijing Institute of Technology have demonstrated thermally stable, MA‑free all‑perovskite tandem solar modules by using a p‑π conjugated additive, semicarbazide hydrochloride (SHCl), to control the crystallization of FACs (FA‑Cs) Pb‑Sn perovskites.

(A) Photograph of the all-perovskite tandem module. (B) Cross-sectional SEM image of the tandem solar device. Image from: Science Advances

All‑perovskite tandems already reach ~25% PCE at module scale, but narrow‑bandgap Pb‑Sn subcells typically rely on thermally unstable methylammonium (MA), and simply replacing MA with Cs‑rich FACs compositions causes rapid, nonuniform crystallization that degrades large‑area film quality. The team tackles this by introducing SHCl into FACs Pb‑Sn precursor solutions, where SH⁺ and Cl⁻ ions cooperatively regulate nucleation and growth: SHCl reacts with CsI (SHCl+ CsI → SHI + CsCl), forming CsCl and SHI, and strongly coordinates with Cs⁺ via its carbonyl group, which lowers Cs solubility, increases supersaturation, and drives a short “burst” of homogeneous nucleation followed by slower crystal growth.

Researchers at Rice University, University of Cambridge, Artois University, Lawrence Berkeley National Laboratory, DirectH2, Rennes University, Northwestern University and Lille University have developed a chloride-based coadditive strategy that stabilizes the black phase of formamidinium lead iodide (FAPI) while preserving its excellent efficiency.

The formation and degradation pathways for extremely stable Cl-doped FAPI. Image credit: Science

FAPI is an attractive perovskite for single-junction solar cells because of its near-optimal 1.45-1.5 eV bandgap and strong thermal stability, but its photoactive cubic black α-phase (3C-FAPI) is unstable at room temperature and tends to reconstruct into a nonperovskite yellow hexagonal δ-phase (2H-FAPI), which lowers device performance. Previous attempts to stabilize 3C-FAPI by alloying with MA, Cs, and Br could suppress this transition, but they introduced phase segregation and long-term instability. The key challenge has been to lock in the black phase without sacrificing durability.

Researchers at the University of Queensland and Southwest University have developed a vapor-based fabrication strategy for lead-free tin-based halide perovskite (THP) indoor solar cells, addressing challenges in crystallization control while achieving high efficiency under low-light conditions.

A central challenge in thermally evaporated THP films is their complex and poorly controlled crystallization kinetics, which often leads to defects and performance losses. To overcome this, the team introduced formamidine acetate (FAAc) as a vapor-deposited additive during the formation of FASnI₂Br films. FAAc coordinates with SnI₂ to form a metastable SnI₂-FAAc intermediate phase. This intermediate slows and regulates the solid-state reaction pathway, allowing more controlled crystal growth. At the same time, FAAc reduces the surface free energy of the underlying SnI₂ layer, enabling more uniform deposition of the subsequent FABr layer. This dual effect - kinetic regulation and improved film wetting - results in higher-quality perovskite films with fewer defects and significantly suppressed trap-assisted recombination.

Researchers at the Huaneng Renewables Corporation, Nanjing University of Posts & Telecommunications, Thermal Power Research Institute and Zhejiang University have developed a molecular surface doping strategy that enables high-performance inverted perovskite solar cells (IPSCs) to be fabricated under high-humidity ambient conditions, addressing one of the key bottlenecks for scalable manufacturing.

While IPSCs have reached certified power conversion efficiencies (PCEs) of up to 27%, their fabrication typically relies on controlled environments such as nitrogen-filled gloveboxes and the use of anti-solvents. Processing in air - especially at relative humidity (RH) above 50% - introduces severe challenges. Moisture accelerates crystallization and promotes hydration-induced phase transitions, leading to structural degradation and a high density of defects. These defects are concentrated at surfaces and interfaces, where their density can be nearly two orders of magnitude higher than in the bulk. In particular, excess p-type defects form at the perovskite/air interface, weakening the n-type surface contact required for efficient IPSCs and increasing nonradiative recombination losses.

Researchers from the University of Science and Technology of China and the University of Colorado Boulder have demonstrated a perovskite diode that acts as both an efficient solar cell and a high‑efficiency LED using the same 800 nm thick absorber layer.

The device embeds porous micrometer‑scale alumina (Al₂O₃) “sponge” islands (∼5 μm wide, 0.5 μm tall) inside the perovskite, allowing a layer thick enough for photovoltaics to also extract light efficiently like an LED. In conventional devices, perovskite LEDs rely on ultrathin, discontinuous layers of about 50 nm, whereas efficient solar cells need layers roughly sixteen times thicker; this architecture reconciles those opposing thickness requirements in a single stack. Surface‑functionalized alumina nanoparticles assemble electrostatically into these islands: one population is coated with negatively charged Me‑4PACz, the other with positively charged ODA, giving a porous, low‑index network the perovskite can grow through without disrupting charge transport.

A recent University at Buffalo (SUNY) study has shown that a fluorinated multifunctional ligand can dramatically improve both efficiency and stability in deep-blue CsPb(Br/Cl)₃ perovskite nanocrystal LEDs by suppressing defect formation and halide ion migration.

Deep-blue PeLEDs require emission in the 460-470 nm range, which can be realized either with mixed-halide CsPb(Br/Cl)₃ nanocrystals or with strongly quantum-confined CsPbBr₃ nanoplatelets. Quantum-confined CsPbBr₃ NPLs have demonstrated 461 nm emission with a 13 nm FWHM and 96% PLQY, enabling REC.2020-compliant deep blue (CIE (0.135, 0.046)), but EQE remains below 7%. Mixed-halide CsPb(Br/Cl)₃ offers a more direct compositional route, yet is prone to halide vacancies and instability, as seen in formamidinium-doped CsPb(Cl₀.₅Br₀.₅)₃ PeNCs that reach 1452 cd m⁻² but only 5% EQE and a peak at 474 nm, slightly red of the target window. In the new work, HFPA-engineered CsPb(Br/Cl)₃ emitters are tuned specifically for operation in the 460-470 nm pure-blue range, directly targeting display-relevant color coordinates.

RenShine Solar has reported several milestones around a 1.2 MW perovskite rooftop installation, the most recent of which is achieving “more than 7,600 kWh in one day”.

The 1.2 MW all‑perovskite distributed photovoltaic power station was completed on rooftops and connected to the grid as a demonstration project, using commercial perovskite modules of 1.2 m × 0.6 m and roughly 130 W output per module. This plant is said to have generated more than 3,000 kWh on its first day of operation and is expected to produce about 1.55 million kWh of electricity annually.

Risen Energy recently announced progress in its heterojunction (HJT) silicon-based perovskite tandem cell technology. Reportedly certified by authoritative institutions, the company’s 1 cm² tandem cell achieved a photoelectric conversion efficiency of 31.95%, with an open-circuit voltage of 1.988V.

This achievement is built upon the company’s long-term expertise in both HJT and perovskite technical routes. As one of the early pioneers in HJT industrialization, Risen Energy has mastered a comprehensive technical ecosystem, ranging from high-efficiency N-type HJT ground-based photovoltaic products to P-type HJT cells designed for the harsh environments of outer space.