Tandem solar cells generate electricity by stacking materials that absorb different portions of sunlight. In the reported architecture, a wide-bandgap perovskite cell is placed on top of a Cu(In,Ga)Se₂, or CIGS, bottom cell. The perovskite captures much of the visible spectrum, while CIGS absorbs lower-energy near-infrared photons that pass through the top layer. This division of the solar spectrum can produce more electrical power than a conventional single-junction cell, whose efficiency is constrained by the trade-off between light absorption and voltage generation.

Although the concept is highly promising, the two-terminal monolithic design is difficult to manufacture. The subcells must be physically integrated, optically aligned and electrically connected through an intermediate recombination layer. Any roughness on the textured CIGS surface, incomplete film coverage or defect-rich boundary can cause carriers to recombine before they are collected. These interface losses reduce the tandem’s voltage and fill factor, while also creating pathways for chemical degradation. The new study focuses on controlling these losses at both critical junctions rather than optimizing only one side of the device.

The first part of the strategy uses a nanoparticle-assisted nickel oxide, or NiOₓ, intermediate recombination layer. NiOₓ serves as a hole-selective material and helps connect the perovskite top cell with the CIGS bottom cell. However, depositing a uniform ultrathin layer over a textured semiconductor surface can be challenging. The researchers used nanoparticles to improve the layer’s ability to follow the underlying topography, producing more conformal coverage and reducing exposed regions where unwanted recombination or electrical leakage could occur.

The intermediate layer must do more than simply connect the two subcells. It needs to support efficient transport of holes from one absorber while allowing electrons from the other absorber to recombine with them in a controlled way. This process, known as interfacial recombination, electrically links the subcells in a monolithic tandem. According to the study, the engineered NiOₓ layer helped optimize the energy-level alignment between adjacent materials, lowering transport barriers and improving the extraction of photogenerated carriers. Better alignment can increase the voltage retained by the tandem and reduce resistive losses during operation.

The second part of the approach targets the boundary between the perovskite absorber and C₆₀, a fullerene-based electron-transport material commonly used in perovskite solar cells. Defects at this interface can act as traps, capturing electrons and holes and allowing them to recombine without contributing to the external current. The researchers introduced a bimolecular co-passivation treatment designed to neutralize multiple types of interfacial defects at the same time. By chemically stabilizing the contact and modifying its electronic properties, the treatment reduced trap-assisted recombination and promoted more efficient electron extraction into C₆₀.

The combined effect of the two interface treatments produced a champion small-area tandem with a reported efficiency of 31.09%. Independent certification measured the device at 30.57%, while its steady-state efficiency reached 30.32% under continuous operation. The active area of this device was 0.0539 square centimetres. Importantly, the strategy also translated to a larger device measuring 1.0298 square centimetres, which achieved a reported efficiency of 29.44% and a certified value of 28.85%. Maintaining performance as device area increases is a major challenge because larger cells are more vulnerable to coating defects, current non-uniformity and resistance losses.

The results are particularly notable because efficiency was not achieved at the expense of durability. The optimized devices retained approximately 94% of their initial efficiency after more than 3,500 hours of storage. Under continuous operation, they preserved about 91% of their starting performance after more than 750 hours. When heated to 70 degrees Celsius, the devices retained roughly 90% of their efficiency after 960 hours. These tests suggest that suppressing interfacial defects can improve both carrier transport and resistance to degradation, although longer testing under standardized outdoor conditions will be needed to determine how the cells perform over years of real-world use.

The study demonstrates that interface engineering may be one of the most effective routes toward practical perovskite/CIGS tandem photovoltaics. Rather than treating the boundaries between layers as passive connections, the researchers designed them as active components that control energy alignment, defect chemistry, carrier recombination and mechanical coverage. The combination of nanoparticle-assisted NiOₓ and bimolecular co-passivation addresses two different bottlenecks in the same device, helping bridge the gap between laboratory-scale efficiency records and scalable tandem manufacturing. If the approach can be adapted to larger modules and industrial deposition processes, it could accelerate the development of high-efficiency solar panels capable of converting a broader fraction of sunlight into electricity.

Subject of Research: Interface engineering for efficient and stable monolithic perovskite/Cu(In,Ga)Se₂ tandem solar cells

Article Title: Improving interface-mediated carrier transport for efficient perovskite/Cu(In,Ga)Se₂ tandem solar cells

Article References: Zeng, L., Wang, W., Tang, L. et al. Improving interface-mediated carrier transport for efficient perovskite/Cu(In,Ga)Se₂ tandem solar cells. Nature Energy (2026). https://doi.org/10.1038/s41560-026-02125-3

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41560-026-02125-3

Keywords: Perovskite solar cells, Cu(In,Ga)Se₂, tandem photovoltaics, interface engineering, NiOₓ, C₆₀, carrier transport, defect passivation, solar-cell stability, photovoltaic efficiency

The traditional reliance on fullerene-based ETLs in tin perovskite solar cells hinges on their ability to facilitate efficient electron extraction and transport, effectively boosting the cell’s overall power conversion efficiency. Despite these benefits, fullerenes are plagued by a range of issues that have slowed the commercial viability of tin-based perovskites. Their synthesis is laborious and expensive, involving several purification steps that raise production costs. More critically, the intrinsic electron mobility of fullerene materials is often insufficient to meet the demands of rapidly developing large-area solar modules. Furthermore, fullerenes interact with the perovskite absorbers in a manner that can cause spatial non-uniformities, ultimately limiting device reliability and lifespan. These limitations have inspired a rigorous search for materials that can emulate fullerene’s conductive properties without inheriting their drawbacks.

Enter the novel class of fluorinated triple-acceptor polymers, designed specifically to address these multifaceted challenges. The polymers, referred to as P1, P2, and P3 in the study, represent a new paradigm in ETL design. Unlike the rigid, spherical fullerenes, these polymers offer tremendous structural flexibility, enabling the formation of continuous and conformal interfaces with tin perovskite layers. This intimate interfacing is critical, as it ensures efficient electron extraction and suppresses non-radiative recombination pathways, which are detrimental to overall device performance. Remarkably, these polymers possess higher intrinsic electron mobilities, a property that dramatically enhances charge transport dynamics within the device architecture.

Among the polymers investigated, P3 stands out due to its optimal energy-level alignment with the corresponding tin perovskite absorbers. This alignment is crucial because it facilitates more efficient electron transfer processes, minimizing energy losses that typically hamper solar cell performance. The study reports that solar devices utilizing P3 as the ETL achieved power conversion efficiencies of 16.06% on small-area cells (0.04 cm²) and 14.67% on larger-area (1 cm²) cells. Notably, these figures have been independently certified at 15.90% and 14.51%, respectively, showcasing reliable performance metrics that are competitive with or even surpass those obtained using traditional fullerene-based layers.

The move away from fullerene architectures toward polymeric ETLs like P3 is more than a marginal improvement; it fundamentally changes the scalability landscape of tin perovskite solar cells. One of the enduring hurdles in perovskite research has been the challenge of uniformly covering large substrates without sacrificing device efficiency or longevity. Polymer ETLs inherently facilitate better morphological control, enabling the formation of uniform layers across centimeter-scale substrates. This capacity for scaling up holds the promise to bridge the gap between laboratory-scale experimentation and industrial-level production, bringing tin-based photovoltaics closer to widespread commercialization.

A critical aspect of solar cell viability beyond initial efficiency is long-term operational stability. Tin-based perovskites, in particular, have been susceptible to degradation triggered by ambient moisture, oxygen, and continuous illumination. The new polymers incorporate long-alkyl side chains and fluorine substituents, imparting significant hydrophobicity to the ETL surface. This hydrophobic nature effectively repels moisture infiltration while simultaneously mitigating chemical degradation pathways. As a result, devices featuring P3 retained over 85% of their initial efficiency even after 550 hours of continuous exposure to 1-sun illumination—a remarkable demonstration of durability that elevates the material’s prospects for real-world applications.

Beyond performance and stability, the cost and environmental impact of materials remain pivotal considerations in next-generation solar technology development. The fluorinated triple-acceptor polymers introduced here benefit from comparatively straightforward synthesis routes relative to the complex, multistep processes associated with fullerene preparation. This simplicity translates into reduced production costs and less environmental waste, offering a sustainable pathway to scale up manufacturing without compromising device function. These attributes make the polymers especially attractive for tackling one of the most pressing industry demands: affordable and eco-friendly solar solutions.

The implications of employing non-fullerene ETLs ripple through various facets of materials science and device engineering. For instance, the strong and uniform interaction between polymer ETLs and tin perovskite layers helps suppress defects and trap states at the interface, phenomena notorious for hampering efficiency and accelerating degradation. Additionally, this strong interfacial coupling enables greater control over electronic properties, which could lead to further fine-tuning of device architectures and the integration of complementary functionalities such as tandem cell stacking or flexible substrates.

Researchers also underscore the potential versatility of these polymers beyond just tin-based perovskites. Given their tunable chemical structures and energy levels, similar fluorinated triple-acceptor polymers might be adapted to interface effectively with lead-halide perovskites or other emerging photovoltaic materials. This adaptability could broaden the scope of high-performance, stable, and scalable solar cells accessible through this innovative material platform.

The study’s achievement of certified efficiencies at practical device sizes is particularly noteworthy in light of historical challenges in tin perovskite research. While lead-based perovskites have dominated efficiency records, tin alternatives have lagged due to intrinsic instability and suboptimal interfaces. This research knocks down one of the principal barriers—efficient electron transport and interface engineering—demonstrating that tin perovskites can rival their lead counterparts in both efficiency and stability when paired with the right transport layers.

In conclusion, the pioneering work presented in this study elucidates a clear pathway for the evolution of tin-based perovskite photovoltaics. Through the elegant design and implementation of fluorinated triple-acceptor polymer ETLs, these devices achieve superior electron transport properties, better energy alignment, enhanced durability, and scalable fabrication. The breakthrough lays an important foundation for ongoing efforts to develop cost-effective, environmentally friendly, and commercially viable solar energy solutions employing non-toxic tin perovskites. It also signals a critical shift in material design philosophy, highlighting the power of polymer chemistry to overcome longstanding limitations in perovskite solar cell technology.

As the photovoltaic research community digests these findings, future investigations will likely focus on optimizing polymer synthesis, exploring new polymer-family analogs, and integrating these ETLs into advanced device architectures. The promising balance of performance, stability, and manufacturability exemplified by P3 and its counterparts could redefine how tin perovskite solar cells are conceived, manufactured, and deployed. Such material innovations are poised to accelerate the global transition toward sustainable energy with affordable, efficient, and scalable solar technologies.

Ultimately, this work marks a pivotal contribution to the field of next-generation photovoltaics, bridging gaps between academic innovation and industrial application. It not only expands the material toolbox available for energy conversion technologies but also charts a future where fullerene-free, polymer-based ETLs become standard bearers for high-performance tin perovskite solar cells. Through this advancement, the scientific community edges closer to unlocking the full potential of perovskite materials as a cornerstone of renewable energy infrastructure worldwide.

Subject of Research: Advancement of non-fullerene electron transport layers in tin-based perovskite solar cells to improve efficiency, stability, and scalability.

Article Title: Centimetre-scale fullerene-free tin-based perovskite solar cells with a 14.51% certified efficiency.

Article References:
Li, T., He, F., Shen, T. et al. Centimetre-scale fullerene-free tin-based perovskite solar cells with a 14.51% certified efficiency. Nat Energy (2025). https://doi.org/10.1038/s41560-025-01919-1

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41560-025-01919-1

The challenge with perovskite solar cells (PSCs) lies not only in achieving high power conversion efficiencies but also in addressing long-term operational stability and scalability for practical applications. Traditional hybrid perovskites—comprising mixed organic and inorganic components—are plagued by issues such as phase segregation, ion migration, and poor crystallinity, which accelerate degradation and reduce device longevity. The all-inorganic CsPbI₃ perovskite emerges as a superior alternative due to its enhanced thermal stability and resistance to phase segregation, offering a more robust material platform for tandem solar cell architectures.

Yet, developing scalable, semi-transparent CsPbI₃ devices with competitive efficiencies has remained elusive, particularly for mechanistically stacked tandem modules at practical device sizes. One crucial bottleneck is the damage inflicted during the deposition of transparent conductive oxides (TCOs) via magnetron sputtering onto organic charge transport layers. This process can compromise the underlying layers, limiting device lifespan and performance. Conventional buffer layers like MoOx provide some protection but suffer from limited charge transport capabilities, increased parasitic absorption, and present challenges when scaled up.

Addressing these obstacles, the research team engineered a sandwich-like MAM buffer structure whereby a thin silver (Ag) layer is encapsulated between two MoOx layers. This design not only safeguards the fragile organic layers beneath from sputtering damage but also enhances charge carrier transport and optical transparency. A key discovery was the in-situ formation of Ag₂MoO₄ within the MAM layer during fabrication, which acts as an efficient carrier transport facilitator while maintaining high visible light transmission between 400 and 800 nm. This fine-tuned balance of electrical and optical properties is critical for optimizing semi-transparent solar cells.

The improved MAM buffer layer facilitated semi-transparent CsPbI₃ solar cells to achieve a remarkable power conversion efficiency (PCE) of 18.86% on small active areas (0.50 cm²). More impressively, when integrated into a four-terminal (4-T) mechanically stacked tandem cell with a TOPCon silicon bottom cell, the devices exhibited a combined PCE of 26.55%. Such efficiencies represent a significant milestone, underlining the potential of this sandwich structure in merging perovskite and silicon technologies effectively.

Beyond small devices, scalability was demonstrated by fabricating larger-area minimodules with aperture sizes of 6.62 cm². These modules maintained impressive efficiencies of 16.67% for the semi-transparent CsPbI₃ perovskite top cells and 26.41% for the complete 4-T tandem minimodules. Notably, this marks the first reported instance of minimodule demonstrations for this particular device architecture, a critical step towards commercial viability and real-world application of perovskite/silicon tandems.

Stability is a paramount concern for perovskite technologies, often restraining their commercial adoption. The new MAM buffer layer also provides a significant advancement here. Mini-modules retained over 93% of their initial performance after more than 1,000 hours of storage, indicating robust long-term environmental resilience. Such stability ensures that devices can withstand practical operating conditions, including temperature fluctuations and light exposure, fundamental for deployment.

The structural design of the MAM buffer layer not only protects the perovskite and adjacent layers but also optimizes optical management. By enhancing visible transmittance without compromising electrical properties, the buffer layer allows for effective light harvesting in both sub-cells of the tandem device. This synergy between structural design and optical-electrical functionality is essential to push the frontier of tandem solar cell efficiencies further.

Looking ahead, the research signals future directions in transparent and photostable interfacial materials aimed at directly integrating the top and bottom cells electrically in series configurations. This would simplify tandem architectures and potentially reduce fabrication complexity and costs. Additionally, alternative fabrication techniques such as doctor blading and slot-die coating are envisioned to produce higher-quality large-area CsPbI₃ films suitable for scalable production.

Scientific inquiries will also focus on the development of new functional buffer layers that minimize efficiency losses related to interfacial defects and parasitic absorption. The pursuit of Ag-free buffer designs is especially pertinent, given the cost and scarcity considerations of precious metals. Finding cheaper, earth-abundant alternatives while retaining the unique benefits of the MAM sandwich configuration could revolutionize the buffer layer’s role in perovskite tandem solar cells.

The realization of mechanistically stacked 4-T tandem mini-modules with record efficiencies and advanced stability demonstrates the feasibility of translating laboratory-scale innovations into practical, scalable photovoltaic devices. This breakthrough paves the way for next-generation perovskite-based tandem solar cells to achieve widespread adoption in the renewable energy landscape, offering a highly efficient, cost-effective, and durable alternative to conventional photovoltaics.

Published in the international journal Materials Futures, this research sets a new benchmark for the design of buffer layers in perovskite photovoltaic technology. It underscores the critical interplay of material science, device engineering, and scalable fabrication technologies necessary for commercializing high-performance solar cells. The insights from this study can expedite the integration of perovskite/silicon tandem photovoltaics into diverse applications, from building-integrated photovoltaics to large-scale solar power plants.

In summary, the MoOx/Ag/MoOx sandwich buffer layer stands as a transformative innovation in the quest for high-efficiency, scalable, and stable semi-transparent perovskite solar cells and tandem modules. By combining protective, electrical, and optical functionalities in a single tailored layer, this technology addresses long-standing challenges in perovskite solar cell fabrication and opens new avenues for the practical realization of next-generation photovoltaics.

Subject of Research: MoOx/Ag/MoOx sandwich structured buffer layers for high efficiency semi-transparent CsPbI₃-based perovskite solar cells and four-terminal tandem minimodules.

Article Title: Designing MoOX/Ag/MoOX sandwich structured buffer layer for four-terminal CsPbI3/TOPCon tandem minimodules

News Publication Date: 16-Oct-2025

Web References:
http://dx.doi.org/10.1088/2752-5724/ae0c76

References:
Rui Zhang, Bobo Ma, Yuqi Cui, Chengyu Tan, Bingbing Chen, Yiming Li, Jiangjian Shi, Huijue Wu, Yanhong Luo, Dongmei Li, Jianhui Chen, and Qingbo Meng*. Designing MoO_X/Ag/MoO_X sandwich structured buffer layer for four-terminal CsPbI_3/TOPCon tandem minimodules. DOI: 10.1088/2752-5724/ae0c76

Image Credits: Rui Zhang, Dongmei Li and Qingbo Meng from Institute of Physics, Chinese Academy of Sciences, and Bobo Ma and Jianhui Chen from Hebei University.

Keywords

Hybrid solar cells, Perovskites, Semi-transparent tandem solar cells, CsPbI₃ perovskite, TOPCon tandem minimodules, MoOx/Ag/MoOx buffer layer, Power conversion efficiency, Charge carrier transport, Scalable perovskite photovoltaics, Four-terminal tandem solar cells, Photovoltaic stability, Transparent conductive oxides

The core challenge in tandem solar cells lies in the efficient and stable interconnection between the perovskite top cell and the silicon bottom cell. Conventional interfacial layers often suffer from chemical incompatibility, energy level mismatches, and environmental degradation, all of which impede the device’s performance and longevity. Yang and colleagues address these challenges by synthesizing amphoteric coplanar conjugated molecules tailored for optimal electronic alignment and robust chemical interaction at the interface between the two absorber layers. This infiltration of molecular design into device engineering represents a significant leap forward in tandem solar technology.

Amphoteric molecules possess both electron-donating and electron-accepting functional groups, which confer versatile charge transport characteristics. By incorporating these molecules into the interface, the researchers achieved improved charge extraction and reduced recombination losses, thereby boosting the overall device efficiency. The coplanar structure of these conjugated molecules is particularly important—its planar configuration facilitates π-π stacking and strong intermolecular interactions, enhancing charge mobility and stability under operational conditions. This molecular architecture enables a seamless electrical bridge between the perovskite and silicon layers that is both efficient and durable.

The researchers utilized advanced spectroscopic and microscopic techniques to characterize the molecular orientation, energy level alignment, and chemical stability of these interfacial layers. Ultraviolet photoelectron spectroscopy (UPS) confirmed that the energy levels of the amphoteric molecules were well-aligned with the conduction bands of perovskite and silicon, facilitating efficient electron transfer. Meanwhile, X-ray diffraction and atomic force microscopy revealed that the coplanar molecules formed uniform, defect-minimized films, crucial for mitigating charge traps that typically limit device performance.

Stability testing under accelerated aging protocols demonstrated remarkable resilience of the tandem devices featuring the amphoteric molecular layers. Unlike traditional organic interlayers that degrade within hundreds of hours, these newly developed materials maintained over 90% of their initial efficiency after extended illumination and thermal stress. This outstanding durability arises from the chemical robustness of the amphoteric molecules and their strong adherence to both the perovskite and silicon substrates, effectively suppressing common degradation pathways such as moisture ingress and ion migration.

The power conversion efficiency (PCE) achieved by these tandem devices is among the highest reported to date. Yang et al. report champion devices reaching PCE values surpassing 29%, accompanied by negligible hysteresis and exceptional operational stability. Such performance benchmarks place this technological development at the forefront of photovoltaic research and promise tangible impact on the solar industry, where tandem cells are poised to dethrone single-junction silicon cells as the dominant technology.

Beyond performance metrics, the synthetic strategy employed for these amphoteric coplanar conjugated molecules is scalable and compatible with solution processing, offering a cost-effective and industry-friendly pathway for device fabrication. Unlike complex vacuum deposition techniques, solution-based methods can potentially lower manufacturing costs and facilitate the widespread adoption of tandem solar technologies. This compatibility with established fabrication protocols ensures that the materials are not just scientifically intriguing but also practically viable.

The integration of these molecules also brings into focus the fundamental understanding of interfacial phenomena in hybrid photovoltaic systems. By marrying precise molecular engineering with device physics, this work provides critical insights into the role of molecular design in controlling charge dynamics and stability at heterojunction interfaces. These insights could inspire a new generation of tailored interfacial materials across diverse optoelectronic applications, including light-emitting diodes and photodetectors.

Moreover, the amphoteric nature of the molecules introduces a level of tunability previously unexplored in tandem interfaces. By modulating the relative strengths of electron-donating and -accepting segments, one can fine-tune the molecules’ electronic properties to match different perovskite compositions or silicon architectures. This adaptability could accelerate customization of tandem devices for various spectral regions and operational environments, opening avenues toward fully optimized multi-junction solar cells with unprecedented efficiencies.

In addition to their electrical benefits, the coplanar conjugated molecules contribute to morphological stabilization of the perovskite layer by mitigating ion migration—a key degradation mechanism plaguing perovskite solar cells. The structural coherence and chemical passivation provided by these molecules alleviate interfacial instabilities that often trigger phase segregation and decomposition. As a result, the tandem devices exhibit extended operational lifetimes that meet the rigorous standards demanded for commercial deployment.

The research team further validated their findings through detailed device modeling and simulations that correlated molecular properties with device-level performance. Their models corroborate the experimental observations by demonstrating how optimal energy level alignment and reduced recombination rates translate directly into enhancements in open-circuit voltage and fill factor. This intersection of theory and experiment underscores the sophistication and robustness of their approach.

While the work primarily focuses on perovskite/silicon tandem cells, the implications extend to broader hybrid photovoltaic architectures. The principles established here—molecular amphoterism, coplanar conjugation, and interfacial engineering—could be extrapolated to other emerging photovoltaics including organic/organic tandems or perovskite/organic combinations. In doing so, this research opens new paradigms in multifunctional molecular design for energy conversion technologies.

As the quest for sustainable energy intensifies, innovations such as those presented by Yang et al. will be pivotal in bridging the gap between laboratory breakthroughs and real-world applications. Their research not only advances our fundamental understanding but also addresses practical challenges in device fabrication, operational stability, and performance scalability. This milestone paves the way toward affordable, high-efficiency, and durable tandem solar cells that could power the future energy landscape with unprecedented effectiveness.

Looking forward, further refinements in molecular design and interface engineering may unlock even higher efficiencies and longer lifetimes, while integration with flexible substrates and tandem configurations could expand the applicability of these technologies. Collaborations between synthetic chemists, device physicists, and industrial engineers will be essential to translate these scientific advances into commercial devices that can be mass-produced and deployed globally.

In summary, this seminal study introduces amphoteric coplanar conjugated molecules as a transformative class of interfacial materials, enabling perovskite/silicon tandem solar cells to reach new heights in efficiency and stability. Its marriage of innovative chemistry and photovoltaic technology represents a paradigm shift that stands to reshape the solar energy landscape and fast-track the adoption of next-generation tandem photovoltaics worldwide.

Article Title:
Amphoteric coplanar conjugated molecules enabling efficient and stable perovskite/silicon tandem solar cells

Article References:

Yang, D., Fahadi, B., Jia, X. et al. Amphoteric coplanar conjugated molecules enabling efficient and stable perovskite/silicon tandem solar cells. Nat Commun 16, 7745 (2025). https://doi.org/10.1038/s41467-025-62700-2

The fundamental challenge with antimony selenosulfide stems from the inefficiencies in charge carrier dynamics. In a photovoltaic cell, photogenerated electrons and holes must be effectively separated and collected at the respective contacts to generate current efficiently. However, in Sb₂(S,Se)₃ absorbers, charge carriers frequently recombine prematurely, especially near the interfaces and within the bulk material, leading to substantial energy losses. These recombination pathways have thwarted previous efforts to enhance device efficiency, necessitating innovative engineering at the contact and interface layers to mitigate such losses.

Dong and colleagues approached this problem by reexamining the front electrode architecture, particularly targeting the widely used fluorine-doped tin oxide (FTO) substrate. Conventional planar FTO substrates provide reliable conductivity but are limited in their ability to maximize light harvesting, especially as thickness and absorption properties of new materials evolve. By adopting a textured FTO substrate, the research team harnessed enhanced light scattering effects, which significantly increased the optical path length of incident photons within the Sb₂(S,Se)₃ absorber layer. This texture-induced scattering effectively maximizes light absorption, thus generating more charge carriers for extraction.

Yet, the introduction of a textured substrate is a double-edged sword. The very surface irregularities that give rise to enhanced light scattering also create morphological challenges. These include voids and shunt pathways at the interface between the FTO and the critical CdS electron-selective buffer layer, which are detrimental due to increased charge recombination and current leakage. To overcome this, the researchers expertly applied a thin SnO₂ layer using atomic layer deposition (ALD) directly onto the textured FTO prior to CdS deposition.

SnO₂, known for its excellent transparency and proper band alignment with CdS and the Sb₂(S,Se)₃ absorber, provided a uniform and conformal coating over the textured substrate. This conformality ensured a continuous interface without physical defects or electrical discontinuities, effectively eliminating unwanted shunt paths and facilitating better charge transport. The ALD method, renowned for its atomic-level thickness control and uniform deposition in complex geometries, was pivotal in this achievement, enabling coating of the intricate textured FTO surfaces without compromising the delicate CdS layer’s properties.

The cleverly engineered band structure resulting from this FTO/SnO₂/CdS configuration optimized charge carrier extraction by aligning energy levels to reduce interface recombination losses. Simultaneously, within the bulky antimony selenosulfide layer itself, the team refined compositional grading and defect passivation techniques that lowered recombination centers. Consequently, both interface-related and bulk charge recombination were suppressed, unlocking previously unattainable device efficiencies.

The practical outcomes of these innovations were remarkable. Utilizing a sodium selenosulfate chemical bath deposition technique for the Sb₂(S,Se)₃ absorber, the research group fabricated solar cells that achieved certified power conversion efficiencies reaching 10.70%, a significant milestone that edges this technology closer to commercialization viability. This certification adds robustness to their findings, confirming reproducibility and reliability under standardized testing protocols, which are crucial benchmarks for industrial adoption.

Moreover, the researchers demonstrated the versatility and generality of their method by applying it to selenourea-based Sb₂(S,Se)₃ fabrication routes, traditionally different in chemical processing. The approach maintained the same enhancements in charge extraction and overall device performance, suggesting broad applicability across various precursor chemistries in antimony selenosulfide photovoltaics.

An important aspect of this work lies in scalability prospects. Moving beyond small lab-scale devices, the team successfully fabricated solar cells with active areas of 1 cm²—significantly larger than many prototype devices—which retained commendable efficiency and stability. Such scaling is a critical step in transitioning laboratory breakthroughs into industrial-scale manufacturing lines, where surface uniformity, process repeatability, and device longevity become paramount criteria.

The stability exhibited by these solar cells over extended periods, coupled with sustained performance metrics, addresses a frequently overlooked yet vital parameter in photovoltaic technology development. Devices must maintain efficiency over thousands of hours under realistic environmental conditions to offer compelling alternatives to existing silicon-based cells. The findings reported here bode well for the practical deployment of Sb₂(S,Se)₃ solar cells, furnishing confidence that these advances are not limited to transient experimental results.

Interfacing electron-selective layers with well-engineered electrodes elucidates a key principle emerging from this study: the convergence of material science, surface engineering, and precise atomic-scale fabrication techniques can pave the way for unlocking latent photovoltaic potential. Controlling charge carrier pathways at interfaces, which have historically proven to be bottlenecks for emerging thin-film technologies, is now demonstrably achievable with strategic multi-layered designs.

This work also underscores the importance of atomic layer deposition as a versatile tool in photovoltaics. Its ability to deposit ultra-thin, pinhole-free films with meticulous thickness control and compositional tuning on complex topographies embodies a game-changing technological lever. The successful implementation of ALD SnO₂ layers in this context could inspire further adaptations across other thin-film and emerging photovoltaic systems, enhancing interface engineering protocols industry-wide.

The implications extend beyond the laboratory, hinting at a future where earth-abundant and non-toxic materials like antimony selenosulfide can rival commercial solar absorbers in terms of efficiency and reliability. Incorporating textured substrates for enhanced light management combined with meticulously designed electron-selective layers signifies a path forward toward sustainable and economically viable solar technologies—critical components in addressing global energy and environmental challenges.

Ultimately, this breakthrough not only signifies a technical achievement but invites renewed enthusiasm for antimony-based photovoltaic research, motivating further investigations into novel contact materials, absorber optimizations, and large-area device architecture refinements. The dual emphasis on improving optical properties through substrate texturing and minimizing electronic losses via interfacial engineering sets a new paradigm for thin-film solar cell development.

As the field marches forward, questions remain regarding the long-term operational stability under varied climatic conditions, integration with encapsulation technologies, and compatibility with flexible substrates for wearable or building-integrated photovoltaics. Nevertheless, the groundwork established here lays a robust foundation for tackling these challenges systematically.

In conclusion, the work by Dong et al. represents a significant leap in antimony selenosulfide solar cell research, demonstrating that clever electrode design paired with electron-selective layer engineering can decisively overcome detrimental charge recombination hurdles. The attainment of a certified 10.70% efficiency augmented by scalability and stability considerations signals a promising horizon for this emerging photovoltaic class poised to make impactful contributions to the clean energy revolution.

Subject of Research: Charge carrier management and interface engineering in antimony selenosulfide (Sb₂(S,Se)₃) solar cells

Article Title: Carrier management through electrode and electron-selective layer engineering for 10.70% efficiency antimony selenosulfide solar cells

Article References:
Dong, J., Gao, Q., Wu, L. et al. Carrier management through electrode and electron-selective layer engineering for 10.70% efficiency antimony selenosulfide solar cells. Nat Energy (2025). https://doi.org/10.1038/s41560-025-01792-y

Image Credits: AI Generated

Silver bismuth sulfide nanocrystals have emerged as a promising alternative to conventional solar cell materials, which often contain toxic heavy metals such as lead and cadmium. The presence of these hazardous materials has raised serious environmental and health concerns. Silver bismuth sulfide, on the other hand, is abundant and non-toxic, making it a compelling candidate for eco-friendly solar technologies. However, this promising material has faced challenges in performance when synthesized in thicker layers, leading to a drop in electrical efficiency, which raised questions about its practical application in commercial products.

To tackle this issue, the research team engineered a novel thin film with a specially designed mixed structure to facilitate improved electrical flow within the solar cells. By creating a layer that combines different properties—designated as "donor" and "acceptor"—the team optimally manipulated the flow of electricity within the solar cell. This enhancement is integral, as it helps maintain the desired performance characteristics even when the thickness of the active layer is increased.

The results of this innovative approach were striking; when a light-absorbing layer of just 65 nanometers was created—twice as thick as traditional layers—the research team succeeded in sustaining performance while achieving a remarkable power conversion efficiency of 8.26%. This enhancement not only improves electricity generation but also translates into practical applications, such as charging smartphones multiple times or providing extended illumination for LED bulbs.

Professor Choi Jong-min expressed optimism regarding the implications of this research, stating that the advancement significantly boosts the charge diffusion length by facilitating the coexistence of donor and acceptor materials within the same layer of AgBiS2 solar cells. Such progress implies that the next generation of eco-friendly solar technologies will be more versatile and effective, with broader applications in high-efficiency solar cell designs anticipated in the near future.

Significantly, this research collaboration between DGIST and UNIST showcases the foundational role of academic partnerships in technological advancements. The project was notably led by students Kim Hae-jung and Park Jin-young from DGIST, alongside Choi Ye-jin, a combined Master’s and doctoral student from UNIST. Their collective efforts, supported by the Ministry of Science and ICT as well as the National Research Foundation of Korea’s various funding programs, highlight the importance of dedicated research in fostering innovation in renewable energy.

The results of this noteworthy research, which was published on February 19, 2025, in the prestigious journal Advanced Energy Materials, underscore the increasing academic and scientific focus on sustainability within the realm of energy production. This publication serves not only as documentation of the collaborative effort but also as a call to action for further exploration in eco-friendly materials and their applications.

Looking beyond academia, the implications of this research could extend to various sectors seeking to integrate sustainable practices into their operations. These advancements may facilitate wider adoption of solar technologies, influencing legislative frameworks and energy policies focused on reducing carbon footprints and encouraging clean energy deployments.

As the world grapples with escalating climate crises, the pursuit of efficient, eco-friendly, and accessible energy solutions—such as those demonstrated by this research—is more critical than ever. This technology, with its dual benefits of increased efficiency and reduced environmental impact, heralds a significant step forward in the global endeavor toward renewable energy and sustainability.

Given the promising results and innovative methods reported, numerous industry stakeholders will likely monitor this field closely, contemplating opportunities for real-world applications. The continuous evolution of solar technology, particularly with materials like AgBiS2, provides fertile ground for discussions on future energy policies and initiatives aimed at combatting environmental degradation.

The solar cell industry stands at a crossroads, with traditional materials increasingly challenged by the need for safer and more efficient alternatives. The findings from this research may pave the way for new standards within the industry, promoting developments that prioritize environmental safety, technological feasibility, and, ultimately, global energy resilience.

In conclusion, the research conducted by DGIST and UNIST represents a leap toward not only harnessing clean energy but also ensuring that the materials we use in these applications are safe and sustainable. Through continued innovation and collaborative efforts, the goal of transitioning to a green energy future appears increasingly achievable. This exciting breakthrough exemplifies the profound potential of research and development in transforming how we view and utilize renewable energy in modern society.

Subject of Research: Solar Cell Technology
Article Title: Homogeneously Blended Donor and Acceptor AgBiS2 Nanocrystal Inks Enable High-Performance Eco-Friendly Solar Cells with Enhanced Carrier Diffusion Length
News Publication Date: 19-Jan-2025
Web References: Advanced Energy Materials
References: None provided
Image Credits: None provided

Keywords: Eco-friendly solar cells, silver bismuth sulfide, power conversion efficiency, renewable energy, nanocrystals, sustainability, energy technology, clean energy solutions.