Researchers from Fudan University, Nanjing University of Science and Technology, Tongji University, Taiyuan University of Technology, Shanghai Nanoshine Technology, Donghua University and Shanghai University of Engineering Science have reported a milestone in the development of lead-free perovskite photovoltaics through the design of high-performance tin-based perovskite solar cells (TPSCs). Their work demonstrates a record certified power conversion efficiency (PCE) of 17.71% for inverted TPSCs.
Tin-based perovskite absorbers are widely recognized as promising alternatives to their lead-based counterparts due to their lower toxicity, environmental friendliness, and high theoretical efficiency. However, progress in this domain has been hindered by poor interfacial contact, suboptimal hole extraction, and instability caused by facile oxidation of Sn²⁺. To address these challenges, the research team engineered a molecular interfacial modifier, (E)-(2-(4',5'-bis(4-(bis(4-methoxyphenyl)amino)phenyl)-[2,2'-bithiophen]-5-yl)-1-cyanovinyl)phosphonic acid, to improve both interfacial and film quality within inverted-architecture TPSCs.
This phosphonic acid–based molecular film forms a homogeneous buried interface featuring optimized energy-level alignment with the adjacent hole transport layer. The resulting interfacial modification markedly enhances hole extraction and carrier recombination dynamics. Simultaneously, it induces a superwetting surface morphology that promotes the formation of compact, uniform, and defect-suppressed tin-based perovskite films. Such synergistic control over interface energetics and film crystallinity enables superior electronic coupling and reduced non-radiative recombination losses.
The optimized devices achieve a small-area PCE of 17.89% (certified 17.71%), representing the highest reported efficiency among inverted TPSCs. Furthermore, the encapsulated devices exhibit remarkable operational stability, maintaining over 95% of their initial efficiency after 1,344 hours of ambient shelf storage and over 94% following 1,550 hours of continuous illumination under 1-sun conditions. Scaled devices with an active area of 1 cm² deliver a PCE of 14.40%, underscoring the method’s scalability for practical deployment.
According to co-corresponding author Liang Jia, the molecular engineering approach “offers a path to truly green and sustainable solar technologies,” as tin combines low toxicity, abundance, and excellent processability. The research highlights the feasibility of integrating lead-free perovskite films into large-area, low-cost modules suited for building-integrated photovoltaics (BIPV), wearable electronics, vehicle-integrated solar panels, and off-grid renewable systems.
By tuning interfacial design principles and stabilizing tin-based absorbers, this work represents a step toward the commercialization of environmentally benign perovskite photovoltaics, bridging the gap between laboratory success and scalable green energy solutions.
