Despite achieving impressive efficiencies up to 33.2%, perovskite/silicon tandem solar cells face significant challenges, particularly concerning the long-term stability of the perovskite active layer. This instability is a major hurdle impeding their commercial viability. Current strategies to enhance perovskite device stability typically involve packaging technologies, crystal engineering, defect passivation, and bandgap adjustments. However, similar to "stress corrosion" observed in metals, glass, and polymers, perovskites degrade over time due to unavoidable tensile stresses during manufacturing and operation. Microscopically, these stresses disrupt lead-halide orbital interactions, altering structural properties like bandgap and carrier dynamics, lowering phase transition barriers, and facilitating defect formation and ion migration. On a macroscopic scale, they induce cracking and delamination, hastening perovskite degradation, which compromises device performance and reliability.
Recently, researchers from the Ningbo Institute of Materials Technology and Engineering of the Chinese Academy of Sciences have achieved breakthroughs in developing high-efficiency, stable perovskite/silicon tandem solar cells. Building on prior studies of crystalline silicon and perovskite solar cells, the team employed a long-chain anionic surfactant additive. This additive enhances perovskite crystal growth through surface self-segregation and micelle formation while constructing a gel-like framework at grain boundaries to relieve residual stress, minimize defects, inhibit ion migration, and optimize energy level alignment. As a result, unencapsulated perovskite single-junction and perovskite/silicon tandem solar cells maintained 85.7% and 93.6% of their initial performance, respectively, during continuous light exposure under maximum power point tracking.
The findings were published in *Nature Communications* under the title "Long-Chain Anionic Surfactants Enabling Stable Perovskite/Silicon Tandems with Greatly Suppressed Stress Corrosion." This research was supported by initiatives such as the National Key R&D Program, the Science and Technology Development Fund of the Macao SAR, and the University of Macau Research Fund.
*Figure: Mechanism of stress corrosion inhibition by long-chain anionic surfactant (Part 1); test of maximum power point working stability of perovskite single-junction (Medium) and perovskite/silicon tandem (Part 2) solar cells.*
This innovative approach not only addresses the critical issue of perovskite instability but also opens new pathways for advancing the commercial feasibility of tandem solar cells. By integrating sophisticated chemical additives into perovskite fabrication processes, researchers are paving the way for more durable and efficient solar technologies. These advancements hold immense promise for sustainable energy solutions, potentially revolutionizing renewable energy systems worldwide.
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