Methylammonium lead iodide perovskite solar cells have emerged as a rising star in the photovoltaic field, with their power conversion efficiency soaring from 3% in 2009 to over 22% by 2016. Remarkably, this remarkable seven-year advancement rivals the decades-long progress seen in other types of solar cells, making them a global hotspot of intense research and industrial interest. However, the toxicity of lead and its potential environmental harm remain significant barriers to the technology's widespread adoption. As a result, developing lead-free perovskite solar cells has become critically important. For non-lead perovskite films—such as tin-based perovskites—their crystalline properties, film morphology, and defect structures are far more challenging to control. Yet these defects are major culprits behind performance degradation. Therefore, mastering the technology to produce high-quality, low-defect non-lead (tin-based) perovskite films is essential for overcoming the key hurdles hindering the commercialization and large-scale application of this promising yet complex technology.

　　Addressing the critical scientific questions and technical challenges outlined above, Professor Chaoxin Wu from the School of Telecommunications at Xi'an Jiaotong University has led his team in a systematic investigation of innovative, high-quality perovskite film fabrication techniques, their underlying kinetic processes, and the development of high-performance lead-free perovskite solar cells. Notably, his group was among the first internationally to pioneer a "evaporation- spin-coating" method for preparing perovskite films. Leveraging this advanced "evaporation-spin coating/immersion" technique, they successfully overcame key hurdles in tin-based perovskite film formation, achieving high-quality, low-defect tin-perovskite films. Moreover, they have made the world’s first-ever report on room-temperature fabrication of methylammonium tin iodide perovskite solar cells, demonstrating a flexible device with a power conversion efficiency of 3.98%. These groundbreaking findings were recently published in the prestigious international journal *Advanced Materials* (IF 18.96).
 
　　This work has received high praise from the reviewers, who described it as "one of the most effective approaches to overcoming the current bottlenecks in lead-free (tin-based) perovskite films and their corresponding solar cells," and emphasized that it "lays the foundation for realizing higher-efficiency tin-based perovskite solar cells." The first author is affiliated with Xi'an Jiaotong University, with Professor Chaoxin Wu serving as the corresponding author. The first author is Jun Xi, a doctoral student under Professor Wu's supervision. Additionally, Professor Merouri from Northwestern University in the U.S. contributed to part of the research. This study was carried out with support from a key project under the National Major Scientific Research Program and a regular project funded by the National Natural Science Foundation of China.