Efficiency

A team at Yunnan University, led by Hongjun Wu and colleagues, with contributing researchers from Kunming University of Science and Technology, has reported a 20.96% efficient CsPbI_3-xBr_x inorganic perovskite solar cell (IPSC), achieved through a new surface passivation molecule built around a sulfonamide group. The result is described as the highest efficiency reported to date for SnO₂-based IPSCs, and the unencapsulated devices also showed strong long-term stability.

All-inorganic CsPbI_3-xBr_x perovskites are of interest for PV applications because of their thermal stability and suitability for tandem architectures, but their surfaces are prone to undercoordinated Pb²⁺ defects. These form when iodide ions migrate out of the lattice under heat, moisture or illumination, leaving behind halogen vacancies that act as non-radiative recombination centers and degrade both efficiency and long-term performance. To address this, the researchers introduced 4-aminomethylbenzenesulfonamide (4-AMBSA), a π-conjugated molecule carrying both an amino (-NH₂) and a sulfonyl (-SO₂-) group, onto the CsPbI_3-xBr_x surface.

Researchers led by Distinguished Professor Seok Sang-il of the Department of Energy and Chemical Engineering at the Ulsan National Institute of Science and Technology (UNIST) have identified the root cause of a defect that had been holding back the efficiency of inverted-structure perovskite solar cells, and used the finding to raise cell efficiency to 26.3% - matching what's typically achieved in conventional-structure cells. 

The inverted structure in particular has low light loss to the lower layer, which is why it's mainly used as the top cell in tandem solar cells combined with silicon. However, applying the high-efficiency material formulation developed for conventional-structure cells directly to the inverted structure had caused efficiency to plunge to around 18%. Using advanced analysis methods at the Pohang Accelerator Laboratory, the team traced the cause: methylammonium chloride (MACl), an additive that helps crystal growth in the conventional structure, instead induces defects when used in the inverted structure. On the hydrophobic organic material that forms the bottom layer of the inverted structure, the intermediate substance created by MACl escapes belatedly. During this process, gaps and cracks form at the buried interface - the bottom of the perovskite layer - which act as points where charge carriers are lost, reducing efficiency.

Researchers from Guangdong University of Technology have developed a zinc-ion (Zn²⁺) modification strategy that improves both the efficiency and the stability of all-inorganic CsPbBr₃ perovskite solar cells.

All-inorganic CsPbBr₃ perovskites are known for their excellent environmental stability compared with hybrid organic-inorganic perovskites, since they avoid the organic cations (such as MA⁺ and FA⁺) that are prone to degrading under heat, moisture, oxygen and light. That stability comes at a cost, however: CsPbBr₃'s wide bandgap (about 2.3 eV) limits light harvesting, and its films typically suffer from low crystallinity and high defect density, which drive charge recombination and hold back power conversion efficiency (PCE).

GCL Optoelectronic Material (Kunshan GCL Optoelectronic Materials), a subsidiary of GCL Group, has completed a D1 financing round exceeding 100 million yuan (over US$14 million), led by Jinxin Capital, with Sequoia China, Xiang'an Venture Capital and Suzhou Asset Management participating. The company says the funds will primarily support the commercial delivery of its ground-mounted photovoltaic power stations and the verification of space photovoltaic applications.

The D1 round follows a Series C2 round completed in July 2025 that raised nearly 200 million yuan. Since its first angel round in May 2020, GCL Optoelectronics has attracted strategic investments exceeding one billion yuan from companies and institutions including CATL, TCL Group, Tencent, Temasek and Sequoia Capital.

Researchers connected to Chinese flexible-perovskite maker SunFlex have published two separate papers within the same month, addressing two of the field's persistent stability problems: halide segregation in wide-bandgap perovskite/organic tandems, and desorption of the self-assembled monolayers (SAMs) used at the perovskite/electrode interface.

The first paper, from researchers at the Chinese Academy of Sciences and Shanghai Jiao Tong University - including SunFlex co-founder and CAS academician Yongfang Li - tackles a known weakness of wide-bandgap, high-bromide mixed-halide perovskites, which are used as the front cell in perovskite/organic tandem solar cells: they tend to mix unevenly during crystallization and undergo light-induced halide segregation during operation, both of which limit device performance. The team introduced a photo-transformable additive, 4-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzylamine (TDB), into the perovskite precursor solution to address both problems in sequence. During crystallization, TDB suppresses the rapid precipitation of the bromide-rich phase and speeds up halide mixing during annealing, improving initial homogeneity. Then, once the device is under illumination, TDB itself transforms into a new chemical species that adsorbs more strongly onto the perovskite's grain-boundary surfaces, blocking the formation of iodide-related defects and suppressing both defect-assisted carrier trapping and ion migration - the mechanisms behind light-induced halide segregation.

Researchers from Tianjin University, Tianjin Institute of Power Sources, Beijing Institute of Technology, the Shanghai Institute of Micro-System and Information Technology (Chinese Academy of Sciences), the Ningbo Institute of Materials Technology and Engineering (Chinese Academy of Sciences), and Harbin Institute of Technology have developed a perovskite/silicon tandem solar cell for space applications that reached a certified 27.49% power conversion efficiency (PCE) under AM0 (zero air mass) illumination - which the team describes as the highest certified AM0 efficiency reported to date for this type of tandem - while also demonstrating strong resistance to electron and proton radiation and stable output during a real high-altitude balloon flight to nearly 30 km.

Perovskite/silicon tandems are attractive for space power because they combine perovskite's radiation tolerance with silicon's mature manufacturing and near-infrared response, but most previous work has focused on efficiency under standard terrestrial (AM1.5G) conditions rather than the radiation resilience and extreme thermal cycling that low Earth orbit (LEO) actually demands. In LEO, devices cycle between roughly +90°C and -90°C more than 15 times a day and face continuous bombardment by high-energy electrons and protons, which damage semiconductors through ionization and atomic displacement. In a monolithic, series-connected tandem, damage to either subcell drags down the whole device - and the researchers found that the silicon bottom cell is usually the weak link.

Researchers from the Indian Institute of Technology (IIT) Guwahati have designed a multilayer photonic film that both lets more usable sunlight reach a perovskite solar cell and passively cools it, together delivering an absolute power conversion efficiency (PCE) improvement of 3.76 percentage points.

Heat is a persistent problem for solar cells: perovskite solar cells (PSCs) tolerate moderate temperature increases better than crystalline silicon cells, but beyond about 55°C their efficiency drops off faster than silicon's does, and a cell's aging rate roughly doubles for every 10°C rise in operating temperature. Passive radiative cooling offers a way to manage this without consuming any power, by using materials that emit heat efficiently in the "atmospheric window" (8-13 micron wavelengths), a band where the atmosphere is largely transparent and heat can radiate straight out to the cold of space.

Researchers from Nanjing University, JA Solar, Chongqing University, Jiangsu New Energy Development Co. and Jiangsu Guoxin Research Institute have designed a new self-assembled monolayer (SAM) additive molecule that fixes a longstanding defect problem at the buried hole-transport interface of inverted perovskite solar cells, enabling a wide-bandgap perovskite cell with a champion power conversion efficiency (PCE) of 23.7% and a perovskite/silicon tandem device that reaches 33.3% (certified at 33.1%), with no measurable PCE loss after 30 days of outdoor operation.

Device configuration illustration and chemical structures of Me and TTA. Image from: Science Advances

In inverted perovskite solar cells, the SAM sitting beneath the perovskite layer governs how well the perovskite crystallizes and how efficiently charge is extracted at that buried interface. The carbazole-based SAM molecule Me-4PACz is widely used for its strong hole-extraction properties, but it tends to self-aggregate when processed from alcoholic solvents, producing uneven coverage with island-like clusters and pinholes. That patchy coverage weakens binding to both the substrate below and the perovskite above, raises interface defect density, and impairs charge transport - a problem that has proven difficult to solve without sacrificing some other aspect of performance.

Researchers from Tsinghua University and Civil Aviation University of China have developed a perovskite laser cell-thermoelectric (PLC-TE) tandem device that converts an incoming green laser beam into electricity at a power conversion efficiency (PCE) of 38.49%, designed to be embedded in the wing of an unmanned aerial vehicle (UAV) as an in-flight power source.

The work targets laser wireless power transmission (LWPT), an approach to beaming energy over long distances that offers strong directionality, flexible beam-steering and resistance to electromagnetic interference. For UAVs, whose flight time is fundamentally capped by onboard battery capacity, LWPT raises the possibility of a drone that recharges continuously in the air rather than returning to the ground. CsPbBr₃ perovskite is a strong candidate receiver material for this application: its broad bandgap absorbs efficiently across the blue-green range (400-550 nm) that aligns with atmospheric transmission windows, and the material remains stable under the high-temperature, high-energy-photon conditions a concentrated laser beam produces.

Researchers from Taiwan's National Yang Ming Chiao Tung University and Flexwave have developed a self-adaptive interfacial nanostructure (SAIN) for the hole-extraction contacts of inverted perovskite solar cells, reporting a power conversion efficiency (PCE) approaching 20% under standard 1-sun illumination and 38.16% under indoor lighting at 2,000 lux - a figure that climbs above 40% once paired with an optical enhancement film, placing the device among the most efficient indoor perovskite solar cells reported to date.

The team explains that "regular" n-i-p configurations tend to reach higher efficiencies, but inverted PeSCs offer better long-term stability and are easier to stack into multijunction devices, making the p-i-n architecture an attractive target for further improvement. A major bottleneck in inverted PeSCs is the buried hole-transport layer (HTL) sitting beneath the perovskite film. Because the perovskite crystallizes directly on top of it, the HTL's quality shapes both the interface and the growing perovskite layer itself, and a poor HTL drives up non-radiative recombination - carriers lost to defects rather than converted into current, which shows up as low photoluminescence quantum yield in the finished film. Today's leading inverted devices typically grow their perovskite on either a hole-conducting polymer such as poly(triarylamine) (PTAA) or a self-assembled monolayer (SAM) built from carbazole-based molecules. Each has drawbacks: high-quality PTAA is costly to produce, while SAMs are difficult to deposit as a conformal, densely packed layer, which hurts device-to-device reproducibility. Both materials are also hydrophobic, complicating full-coverage perovskite deposition over large areas. Hybrid PTAA-plus-SAM contacts have been explored to combine their strengths, but so far only for standard 1-sun operation, leaving their potential for indoor photovoltaics untested.