Researchers at the Advanced Photovoltaic Materials Laboratory have achieved a significant breakthrough in lead-free perovskite solar cell technology, successfully integrating MXenes to dramatically enhance the performance and stability of Cs2AgBiBr6 devices. This innovation, detailed in a recent study, represents a crucial step towards developing safer, more sustainable alternatives to conventional lead-halide perovskites, addressing a key environmental concern that has hampered the broader commercialization of this promising solar technology.

The team’s approach leverages the unique properties of two-dimensional titanium carbide MXenes (Ti3C2Tx) as an interfacial layer within the Cs2AgBiBr6 double perovskite architecture. Traditional lead-based perovskites, while achieving certified power conversion efficiencies (PCEs) exceeding 25%, face regulatory and public acceptance challenges due to lead’s toxicity. Lead-free alternatives, particularly double perovskites like Cs2AgBiBr6, offer a compelling solution but have historically suffered from low efficiencies, typically below 4% for single-junction devices, and poor stability.

By carefully engineering the interface with MXenes, the researchers achieved a notable improvement in PCE, pushing the lead-free Cs2AgBiBr6 solar cells to a certified efficiency of 6.8%, a substantial leap for this material class. The MXene layer facilitates superior charge extraction and transport, effectively passivating defects at the perovskite-transport layer interface. This interfacial optimization not only boosts efficiency but also significantly enhances the operational stability of the devices under ambient conditions, retaining over 90% of their initial efficiency after 1,000 hours of continuous operation, a critical benchmark for commercial viability.

Dr. Anya Sharma, lead researcher on the project, stated, “Our work demonstrates that MXenes are not just excellent conductors but also powerful tools for defect passivation in complex halide perovskite systems. This breakthrough with Cs2AgBiBr6 is a testament to the potential of advanced materials engineering to unlock the full promise of lead-free photovoltaics, making them a more attractive proposition for niche applications and eventually, mainstream solar markets.” The enhanced charge carrier mobility and reduced recombination losses observed are attributed to the favorable work function alignment and high conductivity of the MXene interlayers.

This development positions lead-free perovskites closer to market readiness, particularly for applications where flexibility, transparency, and environmental safety are paramount, such as building-integrated photovoltaics (BIPV), wearable electronics, and indoor solar cells. While current efficiencies still trail lead-based counterparts, the rapid progress in lead-free materials, coupled with innovative interfacial strategies like MXene integration, signals a robust trajectory for a new generation of non-toxic, high-performance solar technologies. The global market for perovskite solar cells is projected to grow significantly, and advancements in lead-free options will be crucial for capturing a larger share of this expansion, particularly in environmentally conscious markets.