Perovskite Solar

The fabrication of perovskite/Si tandem solar cells often encounters the challenge of selecting a suitable sputtering buffer layer (SBL) to prevent damage during the transparent electrode deposition. In their recent work, researchers from China's Northwestern Polytechnical University and Shaanxi Joint Laboratory of Graphene (NPU), Chinese Academy of Sciences and Ningbo New Materials Testing and Evaluation Center Co. developed a perovskite-silicon tandem solar cell that uses an indium oxide sputtering buffer layer to protect the perovskite absorber and the electron transport layer from damages that might occur during the electrode deposition process. The new layer not only granted this protection but also showed strong optical and electrical properties. 

The team introduced the indium oxide (In₂O₃) buffer layer via e-beam deposition to fabricate semi-transparent perovskite solar cells. The optical transmittance and electrical conductivity of In₂O₃ highly depend on the deposition rate. High deposition rate results in high ratio of metallic indium in the film, which causes severe parasitic absorption. A 20 nm-thick In₂O₃ film deposited at lower rate demonstrated high conductivity, transmittance and robust protection during sputtering. 

Power Roll, developer of flexible PVs that feature  a unique combination of microgrooves and perovskites, has signed a Memorandum of Understanding (MOU) with Amcor, a global packaging solutions provider.

Power Roll and Amcor’s collaboration will be focused on advancing solar-powered energy by developing a lightweight solar photovoltaic film that aims to deliver a low-cost alternative to silicon solar panels. The company has a clear focus on capitalizing on growing market opportunities, focusing on the commercialization of its solar PV microgroove technology, which is not reliant on rare earth minerals and can be manufactured using roll-to-roll processes.

An international team of researchers, led by the University of Surrey with Imperial College London, recently reported a strategy to improve both the performance and stability for perovskite solar cells by mitigating a previously hidden degradation pathway.

In their new study, the scientists detail how they produced lead-tin perovskite solar cells that reach more than 23% power conversion efficiency (PCE) – which the team says is one of the best results achieved with this material and importantly, a design strategy which improves the lifetime of these devices by 66%. 

Bifacial perovskite solar cells (Bi-PSCs) have attracted substantial attention due to their potential for enhanced power generation, suitability for integration into building structures and applicability in multijunction PV systems. Recently, researchers from the Indian Institute of Technology Bombay reported the fabrication of efficient Bi-PSCs and investigated their unique properties using various characterization techniques, including Lambertian reflection effects through tilt angle arrangements and bottom albedo illuminations. 

The control device achieved a maximum power conversion efficiency (PCE) of 17.46% under front-side 1 Sun AM1.5G illumination. A significant influence of ground Lambertian reflection was observed with tilt angle variations, resulting in an increase in PCE from 17.46% → 18.82% as the tilt angle reached 20°. Additionally, enhancing the rear-side albedo to 0.5 Sun yielded a maximum PCE of 26% with a bifaciality factor of ∼90% at a tilt angle of 20°. 

Chinese Academy of Sciences (CAS) researchers believe that the issue of instability of perovskite solar cells (PSCs) primarily originates from the migration of halide ions—particularly iodide ions (I⁻). Under light exposure and thermal stress, I⁻ migrates and transforms into I₂, leading to irreversible degradation and performance loss. 

To tackle this challenge, the team introduced the additive 2,1,3-benzothiadiazole,5,6-difluoro-4,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) (BT2F-2B) into the perovskite. The strong coordination between the unhybridized p orbital and lone-pair electrons from I⁻ inhibits the deprotonation of MAI/FAI and the subsequent conversion of I⁻ to I₂. The highly electronegative fluorine enhances its electrostatic interaction with I⁻. Consequently, the synergistic effect of BT2F-2B effectively suppresses the decomposition of perovskite and the defect density of the iodide vacancies. 

Researchers at Finland's Aalto University and Tampere University have developed an encapsulation method for perovskite solar cells (PSCs) to address both optical performance losses at the air-cell interface and intrinsic and extrinsic stability challenges. The team's one-step method provides PSCs with shielding from oxygen and moisture-induced degradation as well as in situ patterning for light management. 

In the new method, the entire surface and sides of the solar cells were coated with polydimethylsiloxane (PDMS), and the front-facing surface of the PSC was in situ–patterned using a soft lithography technique. A replica of leek leaf surface structures was created on the PDMS to reduce reflection and increase haze. The scientists explained that leek leaf replicas, previously used as add-on layers for PSC devices, have shown promise due to their optical and self-cleaning properties. 

Three research projects by City University of Hong Kong (CityUHK) scholars have been awarded funding under the 2024/25 National Natural Science Foundation of China (NSFC) and the Research Grants Council (RGC) Collaborative Research Scheme (CRS), amounting to over HK$8.8 million (around USD$1,130,000). Additionally, five CityUHK scholars have been awarded funding from the 2024/25 NSFC/RGC Joint Research Scheme (JRS), with total funding exceeding HK$6 million (over USD$770,000). 

Among the CityUHK research projects awarded funding under the Collaborative Research Scheme is  “Theoretically Guided Material Design, Syntheses and Device Engineering for Efficient and Stable Perovskite/Organic Tandem Solar Cells”, led by Professor Zeng Xiaocheng, Head and Chair Professor of the Department of Materials Science and Engineering, which aims to develop high-performance perovskite/organic tandem solar cells with efficiencies exceeding 28%, promoting the development of sustainable clean energy while advocating global carbon neutrality.

It was reported that China-based UtmoLight has developed a 450 W perovskite solar module with a 16.1% efficiency rating. It claims that the panel is currently the largest perovskite PV module available.

The new module reportedly covers an area of 2.8 square meters, uses dual-glass encapsulation and features an open-circuit voltage of 190.7 V, a short-circuit current of 3.19, and a fill factor of 73.7%.

Researchers from Ecole Polytechnique Fédérale de Lausanne (EPFL), North China Electric Power University, Westlake University, Lomonosov Moscow State University and others have described the addition of N,N-dimethylmethyleneiminium chloride ([Dmei]Cl) into perovskite precursor solutions to produce two cations in situ—namely 3-methyl-2,3,4,5-tetrahydro-1,3,5-triazin-1-ium ([MTTZ]⁺) and dimethylammonium ([DMA]⁺) cations - that enhanced the photovoltaic
performance and stability of perovskite solar modules.  

A schematic of the roles of [MTTZ]⁺ and [DMA]⁺ in the 3D perovskite matrix. Image from: Science

The team explained that the in situ formation of [MTTZ]⁺ cation increased the formation energy of iodine vacancies and enhanced the migration energy barrier of iodide and cesium ions, which suppressed nonradiative recombination, thermal decomposition, and phase segregation processes. 

The formation of a homogeneous passivation layer based on phase-pure two-dimensional (2D) perovskites is a challenge for perovskite solar cells, especially when upscaling the devices to modules. Researchers from China's Wuhan University of Technology, Xidian University, University of Electronic Science and Technology of China and Germany's Technical University of Munich have revealed a chain-length-dependent and halide-related phase separation problem of 2D perovskite growing on top of three-dimensional perovskites. 

The scientists have demonstrated that a homogeneous 2D perovskite passivation layer can be formed upon treatment of the perovskite layer with formamidinium bromide in long-chain ( >10) alkylamine ligand salts.