The strategy was developed by a research team led by Prof. Ye Jichun at the Ningbo Institute of Materials Technology and Engineering of the Chinese Academy of Sciences, in collaboration with Soochow University, Zhejiang Gonda Electronic Technology Co., Ltd., and JA Solar Technology Co., Ltd. Their findings, published in Matter, combine a specially engineered aluminum-free silver paste with a laser-based contact treatment known as laser-enhanced contact optimization, or LECO.

Crystalline silicon remains the dominant material in the global photovoltaic industry, but manufacturers are under intense pressure to extract more electricity from every wafer while lowering production costs. TOPCon cells have emerged as one of the leading candidates for this next stage of development because they can be integrated into manufacturing lines used for conventional silicon cells. Their structure places an ultrathin oxide layer and a doped silicon contact beneath the metal electrode, separating surface passivation from charge collection.

That separation is crucial. Solar-cell surfaces contain defects that can act as recombination centers, allowing electrons and holes generated by sunlight to annihilate before they can contribute to an electric current. The tunnel oxide and doped contact in TOPCon devices suppress this recombination while still allowing charge carriers to pass through. In principle, the architecture offers both excellent electronic passivation and low contact resistance. In practice, however, the process used to form metal electrodes can undermine both advantages.

Conventional TOPCon metallization often relies on silver-aluminum pastes that are fired at high temperatures. The heat helps the metal penetrate and establish an electrically conductive connection, but it can also degrade the passivation layer, disrupt the silicon lattice, and promote aluminum-induced alloying. These effects increase recombination and electrical losses. At the same time, screen-printed metal lines tend to become wider during processing, covering more of the light-facing surface and reducing the amount of sunlight that reaches the silicon absorber.

The researchers addressed the problem by redesigning the silver paste at the molecular level. Their aluminum-free formulation was engineered to have a carefully controlled molecular configuration and a strong intermolecular hydrogen-bonding network. These features give the paste high thixotropy, meaning it flows under the force of screen printing but rapidly regains its shape once the printing pressure is removed. The result is a narrow, sharply defined electrode that maintains its geometry during subsequent processing.

This shape retention enabled the team to produce front metal gridlines with an aspect ratio of 55%. A high aspect ratio allows a gridline to remain relatively tall while keeping its footprint narrow. That geometry reduces optical shading, allowing more photons to enter the cell, while preserving enough cross-sectional area for efficient lateral current transport. The aluminum-free composition also reduces the chemical aggressiveness of the paste, helping protect the passivation structure beneath the electrode.

The second part of the innovation is the LECO process. Instead of exposing the entire front contact to prolonged, high-temperature firing, a single-frequency laser scans the printed gridlines while the cell is held under reverse bias. The electrical bias drives carriers through the device, while the laser produces localized Joule heating in selected regions. Together, these effects generate the conditions needed to establish low-resistance electrical contacts at discrete points.

This localized reaction is fundamentally different from conventional firing. Rather than broadly disturbing the silicon and oxide layers across the entire electrode area, LECO confines contact formation to carefully controlled sites. The approach minimizes lattice disruption and avoids the extensive aluminum-related damage associated with traditional silver-aluminum metallization. The newly designed paste is essential because it can withstand the laser-assisted process while maintaining narrow, well-defined gridlines.

The combined effects improved both charge extraction and light collection. The resulting TOPCon cells achieved a certified efficiency of 26.31%, while their short-circuit current density reached 41.98 milliamperes per square centimeter. Short-circuit current density, commonly abbreviated as Jsc, measures the current generated per unit area when the cell operates at zero external voltage. The reported value is particularly significant because it reflects the enhanced spectral response and reduced optical shading of the devices, and was described by the researchers as the highest certified Jsc reported for large-area TOPCon solar cells at the time of publication.

The achievement suggests that the future of high-efficiency silicon photovoltaics may depend not only on new absorber materials or more complex cell architectures, but also on microscopic control of how metal contacts interact with semiconductor surfaces. By resolving the usual trade-off between low contact resistance and strong passivation, the synergistic metallization strategy offers a route that is compatible with industrial production. If scaled successfully, it could help manufacturers increase the output of TOPCon modules without requiring entirely new factory infrastructure, bringing more electricity from the same area of silicon and potentially accelerating the next wave of solar-power deployment.

Subject of Research:
A synergistic metallization strategy for improving the efficiency of tunnel oxide passivated contact (TOPCon) solar cells.

Article Title:
26.31%-Efficiency TOPCon Solar Cells Enabled by Synergistic Metallization with Reduced Optical Shading and Contact Resistance Losses

News Publication Date:
6-Aug-2026

Web References:
https://doi.org/10.1016/j.matt.2026.102965

References:
Matter, DOI: 10.1016/j.matt.2026.102965

Keywords

TOPCon solar cells, photovoltaic technology, solar-cell efficiency, metallization, aluminum-free silver paste, laser-enhanced contact optimization, LECO, crystalline silicon, passivation, contact resistance, optical shading, solar energy

At the heart of this breakthrough lies the intricate interface between perovskite materials and tunnel oxide passivated contact (TOPCon) silicon wafers. Unlike traditional thicker silicon wafers, the thin wafers employed in tandem solar cells exhibit a unique combination of reduced thermal mass alongside enhanced thermal conductivity. This dual characteristic accelerates heat transfer profoundly during the deposition of the perovskite subcell, resulting paradoxically in an adverse effect on the quality of the perovskite film. Specifically, the rapid thermal flux induces an expedited crystallization process of the perovskite layer, leading to morphological inconsistencies and ultimately compromising the efficiency of the solar cell assembly.

The challenge posed by this rapid crystallization phenomenon is far from trivial; it manifests as voids and non-uniformities within the perovskite layer, alongside the undesirable segregation of halide components. These structural and compositional defects cascade into elevated non-radiative recombination losses, significantly detracting from the power conversion efficiency (PCE) of the tandem solar cell. Notably, these shortcomings stem directly from the interplay between the wafer’s physical properties and the perovskite layer’s crystallization kinetics, underscoring the complex material science challenges inherent in tandem device fabrication.

Confronting this issue, researchers have introduced a novel approach that leverages the chemical properties of 2-mercaptobenzothiazole (MBT) as an additive during perovskite film formation. This molecule exhibits a fascinating dual-mode binding with organic cations in the perovskite matrix, serving to carefully modulate the crystallization dynamics. By acting as a molecular ‘rheostat’, MBT slows down the otherwise precipitous crystallization triggered by the wafer’s enhanced thermal conductivity, permitting a more controlled and defect-resistant perovskite growth.

The impact of MBT on film morphology is significant: the additive fosters improved uniformity across the perovskite layer while simultaneously eliminating voids and suppressing the halide segregation phenomenon that had previously jeopardized film performance. This refined structural control contributes to a drastic reduction in trap-assisted recombination pathways. Demonstratively, the trap-assisted recombination rate declines from an alarming 3.2 × 10^5 cm s^−1 to a markedly improved 4.3 × 10^4 cm s^−1, signaling a substantial mitigation of non-radiative losses and implying improved charge carrier lifetimes within the active layer.

This molecular engineering approach does more than just improve film quality; it fundamentally boosts the device-level metrics of tandem solar cells integrating perovskite on industrial TOPCon silicon wafers. The two-terminal monolithic tandem devices fabricated using this technology have achieved a certified stabilized PCE of 32.76%, a remarkable milestone that positions such tandem cells at the forefront of solar efficiency benchmarks. Beyond raw efficiency improvements, these cells exhibit impressive operational stability, maintaining 91% of their initial efficiency after 1,700 hours of continuous illumination under standard testing conditions, underscoring their robustness for practical deployment.

From a technological perspective, this work exposes a previously underestimated crystallization problem specific to the interface of industrial silicon wafers and perovskite layers. The revelation not only deepens the fundamental understanding of perovskite crystallization under realistic fabrication conditions but also equips scientists and engineers with actionable strategies to integrate perovskite solar cells more seamlessly into the existing silicon photovoltaic infrastructure. Such integration is crucial if perovskite-based devices are to transition from laboratory prototypes to widespread commercial applications.

Moreover, the insights gained here pertain specifically to the unique thermal environment experienced by perovskite films on thin, thermally conductive silicon wafers, a scenario increasingly relevant as the industry moves towards thinner, more efficient silicon backbones. By addressing the root causes of rapid crystallization kinetics, researchers could circumvent the need for complex processing modifications or lower-throughput fabrication steps, thereby preserving scalability and cost-effectiveness.

This nuanced control over perovskite film formation through dual-mode chemical binding represents a bridge between the granular molecular chemistry of active layer materials and large-scale device engineering. It illustrates how additive chemistry can be harnessed to tune perovskite crystallization in pathways previously inaccessible, highlighting a crucial link between materials science and renewable energy technology development.

The ramifications of these findings extend beyond perovskite-TOPCon tandem solar cells. By illuminating mechanisms by which thermal properties of substrates influence perovskite layer quality, the study sets a precedent for tailoring interfaces in other layered photovoltaic architectures. Future explorations may seek to identify additional additives with similar or enhanced dual-binding characteristics or explore synergistic effects with co-additives to further elevate efficiency and operational stability.

Crucially, the reported advancements also hold promise for addressing long-standing concerns regarding the environmental stability of perovskite solar cells. The enhanced morphological uniformity and suppressed ion segregation inherently contribute to improved resilience under prolonged operational conditions, a key parameter for real-world energy production scenarios.

Industry stakeholders and academic researchers alike will find in this work a compelling demonstration of how subtle chemical modifications can unlock performance gains that are otherwise unattainable due to the physical constraints imposed by device architecture and material properties. The successful certification of high-efficiency tandem cells marks an important validation step toward commercialization, signaling that perovskite-silicon tandem solar cells are not merely experimental novelties but tangible energy solutions on the cusp of market readiness.

Looking forward, this pioneering strategy presents a foundational platform upon which future innovations can build. By continuing to refine the chemistry at the perovskite-silicon interface and understanding the dynamic thermal processes shaping crystallization, the photovoltaic community is poised to further enhance the integration of emergent materials with conventional technologies, enabling the next generation of high-efficiency, cost-effective, and durable solar energy devices.

In essence, the introduction of 2-mercaptobenzothiazole as a crystallization modulator has addressed a critical bottleneck in tandem solar cell fabrication, opening new avenues for the realization of ultra-efficient perovskite/silicon tandem photovoltaic modules. This advance symbolizes the power of targeted molecular design in solving complex fabrication challenges, propelling solar energy technologies toward higher efficiency thresholds and broader adoption in the global renewable energy landscape.

Subject of Research:
Additive-assisted modulation of perovskite crystallization dynamics on industrial tunnel oxide passivated contact (TOPCon) silicon wafers to boost tandem solar cell efficiency and stability.

Article Title:
Additive-assisted perovskite crystallization on industrial TOPCon silicon for tandem solar cells with improved efficiency.

Article References:
Zhou, Q., Guo, R., Liu, S. et al. Additive-assisted perovskite crystallization on industrial TOPCon silicon for tandem solar cells with improved efficiency. Nat Energy (2026). https://doi.org/10.1038/s41560-026-02010-z

DOI:
https://doi.org/10.1038/s41560-026-02010-z

Currently, the global solar industry predominantly utilizes the passivated emitter rear cell (PERC) design, which has established itself as the standard technology in photovoltaic (PV) systems. However, the emergence of the more advanced tunnel oxide passivated contact (TOPCon) photovoltaic architecture has prompted a reevaluation of environmental impacts associated with solar panel manufacturing. While both technologies serve the purpose of converting sunlight into electricity, the shift to TOPCon represents a critical juncture that could substantially influence the sustainability profile of solar energy production.

The extensive research, recently published in the esteemed journal Nature Communications, undertook a comprehensive life-cycle assessment to compare the manufacturing processes and emissions profiles of the existing PERC technology against the newly developed TOPCon technology. This study illuminates the potential for a significant reduction in the environmental impacts associated with the manufacturing of solar panels, particularly as global deployment is set to increase at an unprecedented rate.

Dr. Nicholas Grant, an Associate Professor at the University of Warwick and one of the lead authors of the study, emphasizes the need for an urgent reframing of solar manufacturing practices as it scales up to meet global energy demands. He asserts that a rigorous focus on understanding the environmental footprint of photovoltaic technologies is crucial. The research suggests that by implementing targeted improvements throughout the solar supply chain, it is feasible to prevent the emission of twenty-five gigatonnes of CO₂ from manufacturing activities by the year 2035, thereby aligning industry growth with sustainable practices.

Astoundingly, the results of the life-cycle assessments indicate that the production of TOPCon panels outperforms the existing PERC technology in fifteen out of sixteen environmental categories. A noteworthy finding is that TOPCon technology could deliver a 6.5% reduction in climate-altering emissions per unit of electricity generated, although an increase in silver consumption stands as its primary environmental downside. This detail underscores the delicate balance that must be struck between technological advancement and resource depletion, particularly concerning critical minerals essential for manufacturing processes.

Moreover, the geographical context in which photovoltaics are manufactured emerges as a pivotal factor influencing their overall carbon emissions. The study emphasizes that solar panels produced utilizing low-carbon electricity sources—such as those prevalent in Europe—yield significantly lower emissions compared to those manufactured via fossil-fuel-heavy energy grids. This finding suggests that policymakers should advocate for manufacturing facilities powered by renewable energy to maximize the environmental benefits of solar technologies, encouraging a broader transition to cleaner energy sources.

The comprehensive analysis culminates in an optimistic projection: if TOPCon technology becomes widely adopted, combined with advancements in manufacturing processes and a concerted effort to decarbonize the energy grids worldwide, solar manufacturing emissions could be reduced by an impressive 8.2 gigatonnes of CO₂ equivalent by 2035. This figure represents approximately 14% of the current global annual carbon emissions, illustrating the profound impact that solar energy solutions can have on mitigating climate change.

In addition to the prospective reductions in carbon emissions from manufacturing, the anticipated deployment of photovoltaics between 2023 and 2035 is set to displace more than 25 gigatonnes of emissions linked to fossil fuel energy production. This dual benefit underscores solar power’s invaluable role in transitioning energy systems towards a more sustainable future while simultaneously enhancing energy security for nations increasingly reliant on a stable electricity supply.

As the urgency for addressing climate change continues to rise, the significance of solar photovoltaics as a sustainable technology cannot be overstated. Senior author and Northumbria University professor, Neil Beattie, advocates for the immediate and widespread adoption of solar PV technologies. He highlights their potential to substantially reduce greenhouse gas emissions, particularly as global electricity demands surge over the next decade, driven by advancements in transportation, heating systems, and digital infrastructure, including developments in artificial intelligence.

Despite the challenges presented by manufacturing impacts, the research affirms that solar photovoltaics remain one of the most environmentally friendly and sustainable energy generation technologies available throughout their life cycle. The authors advocate for prioritizing the immediate deployment of solar PV systems at a large scale to harness their capacity for reducing carbon footprints while fostering economic growth in the renewable energy sector.

Through the collaboration of leading researchers from prominent UK universities, the study represents a significant leap towards understanding and improving the sustainability of solar energy technologies. Their efforts aim to amplify awareness of the environmental implications of solar manufacturing, paving the way for informed decision-making in material selection, technology evolution, and energy sourcing that will ultimately shield our planet from the adverse effects of climate change.

In conclusion, as the global community grapples with the pressing need for sustainable energy solutions, the revelations from this pivotal research point towards a robust future for solar photovoltaics. The shift to advanced TOPCon technology, combined with strategic manufacturing improvements and a transition to cleaner energy sources, provides a roadmap that could facilitate a monumental reduction in global carbon emissions. The implications of these findings are clear: embracing and implementing these technologies can catalyze a profound transformation towards a more sustainable and resilient energy future.

Subject of Research: Environmental savings from silicon photovoltaics manufacturing
Article Title: Maximising environmental savings from silicon photovoltaics manufacturing to 2035
News Publication Date: 3-Feb-2026
Web References: http://dx.doi.org/10.1038/s41467-026-69165-x
References: N/A
Image Credits: N/A