CIF UV-Ozone Cleaners Empower High-Efficiency Tandem Solar Cell R&D | Client's Breakthrough Published in Nature Energy!

Time：2026-04-16 Click Count：14

A collaborative research team has published a groundbreaking study in the prestigious energy journal Nature Energy (Impact Factor: 60.1), achieving major breakthroughs in high-efficiency crystalline silicon solar cells and perovskite/silicon tandem photovoltaics. Focusing on the deep optimization of Tunnel Oxide Passivated Contact (TOPCon) cell structures, this work not only breaks through the efficiency bottleneck of traditional TOPCon cells but also provides a clear and viable pathway for next-generation, highly stable, and industrially scalable tandem photovoltaic technology, earning high recognition from international peers.

CIF UV-Ozone Cleaner: Critical Interface Treatment

In the fabrication process of perovskite/TOPCon tandem solar cells, interface quality directly impacts carrier transport and the ultimate efficiency of the device. The research team selected the CIF UVO 9 UV-Ozone Cleaner to complete the crucial step of substrate surface hydroxylation.

Through the synergistic effect of ultraviolet light and ozone, the system gently and efficiently removes residual organic contaminants on the substrate surface, enhancing surface energy and wetting uniformity. This lays a solid foundation for the high-quality deposition of subsequent functional layers, including the IZO composite layer, NiOx hole transport layer, and perovskite thin films. Consequently, it effectively reduces interface defects and enhances interlayer adhesion, empowering the device to achieve higher open-circuit voltage and more stable output.

Research outcomes

This study, published in Nature Energy, focuses on the technical breakthroughs and performance optimization of silicon-based and perovskite/silicon tandem solar cells. The core achievements can be summarized in four aspects, simultaneously validating the industrialization potential of the novel cell architecture:

1. Development of High-Efficiency Bifacial TOPCon Cells with a Certified Efficiency of 26.34%
The team designed a Finger TOPCon cell architecture featuring patterned n-type TOPCon finger electrodes on the front and a full-area double-layer p-type TOPCon emitter on the rear. This design breaks through the inherent limitations of front-side recombination losses in traditional TOPCon cells. The fabricated full-size cells achieved a high open-circuit voltage (

V_{o c}

) of 743.2 mV and a fill factor (FF) of 85.0%. The certified power conversion efficiency (PCE) reached 26.34%. Furthermore, the devices demonstrated excellent damp-heat stability with negligible light-induced degradation (LID) and light- and elevated-temperature-induced degradation (LeTID), meeting industrial production requirements.

2. Overcoming Key Fabrication Challenges and Optimizing Core Passivated Contact Structures

Front Textured Surface: Circular pyramid textures were prepared using an ozone-hydrofluoric acid solution. Combined with a Gradient Thermal Field (GTF) to improve polysilicon crystallinity and optimized phosphorus doping concentration ( $3.3 \times 1 0^{20} {cm}^{- 3}$ ), the patterned SiOx/polysilicon (n+) passivated contact achieved low recombination ( $J_{0} = 0.6 {fA cm}^{- 2}$ ) and low specific contact resistivity ( $0.61 m Ω {cm}^{2}$ ).
Rear Planar Surface: A double-layer SiOx/polysilicon (p+) passivated contact structure was developed. By optimizing the tunnel oxide layer growth, polysilicon crystallization, and boron doping parameters, along with a modified silver paste design, the rear contact resistivity was reduced to as low as $0.55 m Ω {cm}^{2}$ , significantly minimizing rear-side recombination losses.

3. Fabrication of Perovskite/TOPCon Tandem Cells with a Certified Efficiency of 32.73%
Using the aforementioned high-performance bifacial TOPCon cell as the bottom cell and integrating it with a wide-bandgap perovskite top cell, a monolithic perovskite/TOPCon tandem solar cell was fabricated. The device achieved a certified PCE of 32.73%, an exceptionally high

V_{o c}

of 1.961 V, an FF of 81.83%, and a short-circuit current density (

J_{s c}

) of 20.40 mA cm⁻². All performance metrics surpass previously reported results for similar tandem cells.

4. Excellent Stability and Compatibility with Industrial Mass Production

The perovskite/TOPCon tandem cell demonstrated outstanding long-term operational stability, retaining 80% of its initial efficiency after 2,000 hours of maximum power point tracking (MPPT) testing under continuous 1-sun illumination in a nitrogen atmosphere at room temperature. Meanwhile, the core fabrication process for the bifacial TOPCon bottom cell is fully compatible with existing photovoltaic industrial production lines. The key fabrication steps for the tandem cell do not require extreme conditions, providing a scalable technical pathway for future industrialization.

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Through innovative TOPCon cell architecture and refined engineering of passivated contact structures, this study successfully achieved the highly efficient integration of patterned n-type TOPCon and double-layer p-type TOPCon for the first time, breaking through the efficiency bottleneck of traditional TOPCon cells. Furthermore, the tandem cells developed based on this bottom cell significantly enhanced both the efficiency and stability of perovskite/silicon tandem solar cells. This work lays a crucial technological foundation for the R&D and industrialization of next-generation, high-efficiency, and low-cost photovoltaic cells.

Original image

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Figure 1 | Simulated potential of power conversion efficiency (PCE) for different TOPCon structures
a) Schematic diagrams of four TOPCon structures, including conventional TOPCon, bifacial TOPCon, finger TOPCon, and bifacial finger TOPCon.
b) PCE potentials and corresponding free energy loss analysis for the four TOPCon structures.

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Figure 2 | Performance of finger TOPCon solar cells
a) Schematic diagram of the finger TOPCon solar cell structure.
b,c) Scanning electron microscopy (SEM) images of the front-side patterned SiOx/poly-Si (n⁺) (b) and rear-side double-layer SiOx/poly-Si (p⁺) passivating contact structures (c).
d,e) Certified current–voltage (I–V) and power–voltage (P–V) curves (d), and external quantum efficiency (EQE) (e) of the finger TOPCon solar cells.
f) Progression of power conversion efficiency (PCE) for interdigitated back contact (IBC) TOPCon solar cells in recent years. (注：原文中的“叉指背接触”在光伏领域通常对应 IBC，若您的论文特指 FBC 结构，可将 IBC 替换为 FBC)
g) Power and free energy loss analysis of the finger TOPCon solar cells.
h–j) Stability of monolithic glass-glass packaged finger TOPCon modules under accelerated testing conditions: damp heat (DH) test (85 ± 2 °C, 85% relative humidity, ambient air, dark) (h); light-induced degradation (LID) test (50 ± 10 °C, ambient air, 1000 W·m⁻² LED solar simulator illumination, 60 h/month) (i); and light and elevated temperature induced degradation (LeTID) test (75 ± 2 °C, ambient air, variable intensity LED solar simulator illumination, 324 h) (j). The initial absolute PCE values in (h), (i), and (j) are 25.82%, 25.86%, and 25.75%, respectively.
Data source: d, ISFH.

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Figure 3 | SiOx/poly-Si (n⁺) Passivated Contact Structure on the Pre-texturing Front Surface

(a) Cross-sectional SEM image of the circular pyramid texture.
(b,c) Top-view SEM images of polysilicon (poly-Si) under a conventional thermal field (b) and a gradient thermal field (GTF) (c).
(d) Cross-sectional SEM image of poly-Si under the GTF condition.
(e) Raman spectra of poly-Si with and without GTF treatment.
(f) Effective minority carrier lifetime as a function of injection level for textured n-Si passivated by SiOx/poly-Si (n⁺), with and without GTF treatment.
(g) Phosphorus doping concentration profile measured by electrochemical capacitance-voltage (ECV) profiling.
(h) Saturation dark current density (

J_{0}

) and implied open-circuit voltage (

i V_{o c}

) as a function of phosphorus doping concentration for textured n-Si passivated by SiOx/poly-Si (n⁺). Error bars represent the standard deviation of 5 samples.
(i) Contact resistivity (

ρ_{c}

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Figure 4 | Rear-side double-layer SiOx/poly-Si (p⁺) passivating contact

a) High-angle annular dark-field (HAADF) image and EDX elemental mapping of the double-layer SiOx/poly-Si (p⁺) structure.
b) Dependence of the implied open-circuit voltage (iVoc) of planar n-Si passivated by the double-layer SiOx/poly-Si (p⁺) on the thickness of the thermally grown SiOx.
c) Raman spectra of boron-diffused polycrystalline silicon films with and without pre-annealing treatment.
d,e) Dependence of the implied open-circuit voltage (iVoc) of planar n-Si passivated by the double-layer SiOx/poly-Si (p⁺) on the crystallinity of poly-Si (p⁺) (d) and the boron doping concentration (e). The bar charts and error bars in (b), (d), and (e) represent the mean values and standard deviations of three samples, respectively.
f) Dependence of the specific contact resistivity (ρc) of the double-layer SiOx/poly-Si (p⁺) on n-Si on the alkali metal oxide content in the silver paste. The error bars for the mean values in (f) represent the standard deviations of six samples.
g) Cross-sectional SEM image of the contact interface between the double-layer SiOx/poly-Si (p⁺) and the silver electrode after firing.

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Figure 5 | Performance of monolithic perovskite/TOPCon tandem solar cells

a) Schematic diagram of the perovskite/TOPCon tandem solar cell structure.
b) Certified current density–voltage (J–V) curve.
c,d) Steady-state power output (c) and external quantum efficiency (EQE) (d) of the device. The inset in (c) is a photograph of the perovskite/TOPCon tandem solar cell.
e) Progression of power conversion efficiency (PCE) for perovskite/TOPCon tandem solar cells (all photovoltaic parameters are detailed in Supplementary Table 4).
f) Long-term maximum power point (MPP) stability tracking of the encapsulated tandem solar cell under continuous illumination (AM 1.5G, 1000 W·m⁻², LED solar simulator) at room temperature in a nitrogen atmosphere. The initial absolute PCE value is 30.58%.