In the relentless pursuit of sustainable and affordable solar energy solutions, thin-film solar cells have emerged as a promising frontier. However, the transition from laboratory-scale devices to commercially viable modules has been hampered by complex challenges in material synthesis, uniformity, and scalability. A cutting-edge breakthrough now appears on the horizon, with researchers unveiling a novel approach to fabricating large-area, solution-processed kesterite solar modules boasting unprecedented efficiencies. This development not only advances the field of multielemental thin-film photovoltaics but also propels sustainable energy technologies closer to mainstream adoption.
The research focuses on Cu_2ZnSn(S,Se)_4, commonly abbreviated as CZTSSe, a quaternary semiconductor compound belonging to the kesterite family. CZTSSe is an attractive candidate for thin-film solar absorbers due to its abundance, environmental benignity, and suitable photovoltaic properties. Yet, despite these advantages, solution processing of CZTSSe films has been notoriously challenging. The primary complications arise from the material’s multielemental composition, which leads to intricate phase transformations and grain growth dynamics during crystallization. These issues often result in non-uniform films with poor electronic quality, severely limiting device performance.
To overcome these obstacles, the group spearheaded by Xiang and colleagues employed a strategic modification in precursor chemistry, specifically tuning the thiourea-to-metal ratio within their solution process. This subtle yet impactful adjustment engenders increased porosity in the initial film matrix, which proves crucial in facilitating uniform chemical reactions vertically through the film thickness. Enhanced reaction uniformity ensures consistent grain growth both laterally and vertically, leading to compact films characterized by large, well-formed grains. These textures are essential to reduce grain boundary-related recombination losses and enhance carrier transport.
The ability to control grain morphology and phase purity at the scale of the whole film marks a significant stride in solution processing of CZTSSe. The researchers fabricated uniform, large-area films with minimal defects and highly consistent optoelectronic properties. The single-junction solar cells derived from these films demonstrated a record single-cell power conversion efficiency reaching 13.4%, a notable achievement for solution-processed kesterite solar absorbers. This benchmark efficiency rivals and, in some cases, outperforms analogous devices processed via more complex vacuum-based deposition techniques.
Scaling beyond laboratory cells, the team successfully transitioned their solution processing technique to fabricate solar modules. A key element of module fabrication involves managing interconnection architecture and mitigating parasitic losses that become increasingly significant with larger area devices. After meticulously optimizing module structural parameters, including contact interfaces and patterning procedures, they managed to significantly reduce shunt pathways and resistive losses—common culprits in module efficiency degradation.
The culmination of this intricate engineering and chemical optimization yielded a CZTSSe solar module with a certified power conversion efficiency of 10.1%, verified by the National Renewable Energy Laboratory (NREL). This certified result is a pivotal milestone, as it authentically demonstrates the viability of solution-processed kesterite modules for commercial-scale applications. What sets this module apart is not only its efficiency but also its remarkably low cell-to-module losses, particularly in metrics such as open-circuit voltage and current density. Minimizing these performance losses during scaling is vital for translating laboratory advances into real-world energy solutions.
Significantly, their work elucidates the mechanisms underpinning film formation dynamics in complex multicomponent semiconductor systems, providing both empirical data and theoretical insights that can be generalized to other emerging thin-film photovoltaics. By precisely engineering film porosity and optimizing precursor chemistry, the solution processing route transforms from a risky, defect-prone approach to a scalable, reproducible, and efficient manufacturing method. This paradigm may well reshape strategies in thin-film solar technology development.
The implications of this advance reach far beyond CZTSSe alone. The approach harnesses solution chemistry to manipulate nucleation and grain coalescence, an approach that can be adapted to other earth-abundant materials such as perovskites, copper-based chalcogenides, and metal oxides. Furthermore, the cost-effective nature of solution processing promises significant reductions in manufacturing expenditures relative to vacuum-based deposition systems, improving the economic competitiveness of solar power.
Notably, the team addressed a critical yet often overlooked aspect of module performance—patterning-induced shunting and non-ideal electrical contacts. These subtle defects can drastically reduce the fill factor and overall efficiency if not adequately mitigated. By refining the module architecture and applying targeted structural modifications, Xiang and colleagues achieved a balance that preserves device integrity while maintaining scalable manufacturing processes.
This holistic treatment of both chemical synthesis and module engineering embodies a maturation of the solution-processing field. It exemplifies how nuanced control at the molecular and materials level synergizes with macroscopic device design to deliver tangible, high-performance photovoltaic modules. It marks an important step toward the practical deployment of eco-friendly, sulfide/selenide-based solar technologies within the global energy landscape.
Future directions inspired by this work may include exploring alternative chalcogen sources, various metal stoichiometries, or complementary passivation strategies to further suppress defects and enhance charge-carrier lifetimes. Additionally, integrating tandem architectures with perovskites or silicon could leverage the solution-processed CZTSSe modules as efficient bottom cells, unlocking higher overall power conversion efficiencies.
This breakthrough stands as a beacon for sustainable solar materials innovation, combining materials science excellence with pragmatic engineering. The certified 10.1% efficiency module underscores the maturation of solution-processed kesterite photovoltaics into a commercially relevant contender and galvanizes further research efforts aimed at achieving even higher yields, larger module sizes, and enhanced long-term stability.
In light of global energy demands and climate goals, scalable, low-cost thin-film solar modules derived from earth-abundant materials will play a critical role in decarbonizing electricity generation. The demonstration of uniform, large-area CZTSSe films via solution processing with improved crystallinity and minimal phase heterogeneity not only solves fundamental material challenges but also demonstrates commercial potential, bringing us one step closer to grid parity and widespread renewable adoption.
The elegance of this solution chemistries-driven approach lies also in its compatibility with flexible substrates and roll-to-roll manufacturing, promising revolutionary shifts in how solar modules are produced and integrated into diverse environments. This could enable deployment in building-integrated photovoltaics, portable systems, and novel applications unforeseen in conventional rigid solar panels.
The research by Xiang et al. charts a clear and compelling path forward for the kesterite community and broader photovoltaic research fields, affirming that intricate materials chemistry and module-level engineering must evolve hand-in-hand. Their accomplishment reshapes the narrative around solution-processed multielemental films and elevates the prospects of kesterite-based solar technologies from experimental curiosities to industrially relevant solutions.
This landmark achievement is poised to stimulate significant attention within the scientific community and industry alike, encouraging further exploration into low-cost, scalable thin-film materials. It serves as a paradigm for how meticulous precursor tuning, porosity control, and device optimization can culminate in performance breakthroughs that resonate beyond the laboratory bench, impacting real-world energy infrastructures.
In conclusion, the demonstration of a 10.1% certified efficiency solution-processed CZTSSe solar module heralds a new chapter in thin-film photovoltaics. It showcases that complex multielemental absorbers, once dismissed as too challenging for uniform scalable processing, can now rival their more mature counterparts through inventive chemical engineering and module design. This work stands as a testament to the transformative potential of solution processing, laying a robust foundation for next-generation sustainable energy technologies worldwide.
Subject of Research: Solution-processed Cu_2ZnSn(S,Se)_4 (CZTSSe) thin-film solar modules and film fabrication.
Article Title: Solution-processed kesterite solar module with 10.1% certified efficiency.
Article References:
Xiang, C., Yuan, M., Ding, C. et al. Solution-processed kesterite solar module with 10.1% certified efficiency. Nat Energy (2025). https://doi.org/10.1038/s41560-025-01860-3
Image Credits: AI Generated
Tags: advancements in solar module efficiencychallenges in solar cell fabricationCu2ZnSn(Sefficient thin-film solar cellsenvironmental benefits of kesteriteimproving crystallization in solar filmsinnovative precursor chemistry in photovoltaicsmultielemental semiconductor technologyovercoming material synthesis challengesscalable solar energy solutionsSe)4 photovoltaicssolution-processed kesterite solar modulessustainable energy technologies
