Scientists unveil lead-free solar breakthrough in drive for safer, greener energy

The innovation centres on the use of aliphatic ammonium compounds, specifically butylamine hydroiodide (BAI), to overcome longstanding material limitations in rudorffite solar cells. These include poor silver iodide (AgI) solubility and defect-prone film formation, both of which have historically hindered efficiency and stability in lead-free alternatives.

By integrating aliphatic ammonium additives into the fabrication process, the team achieved a 26% improvement in power conversion efficiency (PCE), reaching a benchmark of 1.97%. This leap was accomplished by tackling three interconnected problems: improving the solubility of AgI, correcting stoichiometric imbalances that cause silver vacancies, and chemically passivating defects that lead to charge recombination.

Microscopic and spectroscopic analyses revealed marked improvements in film quality and structural integrity. Crystals exhibited preferential orientation, surfaces were significantly smoother, and trap densities were substantially reduced. As a result, devices maintained 90% of their performance after 480 hours of continuous illumination—an indicator of remarkable operational stability.

This work not only addresses a critical bottleneck in the advancement of non-toxic perovskite solar cells but also offers a robust foundation for future improvements. The team suggests that further gains could be realised through the incorporation of multiple synergistic additives, refined interfacial designs, and strategic bandgap engineering via elemental doping.

The findings, published in the Materials Futures journal, underscore the potential of aliphatic ammonium engineering as a transformative approach to eco-friendly photovoltaic materials. As concerns over the environmental cost of lead-based perovskites mount, this research represents a timely and practical pathway to safer solar technologies.

Reference: Xinyu Guo, Wenjin Yu, Xiangdong Li, Hantao Wang, Qinyun Liu, Yu Zou, Yunan Gao, Zhijian Chen, Lixin Xiao, Bo Qu. Ag Management of Rudorffites Solar Cells Utilizing Aliphatic Ammonium[J]. Materials Futures. DOI: 10.1088/2752-5724/adcbc7

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