New Molecule Boosts Efficiency in Tandem Solar Cell Technology

A research team led by Prof. Ye Jichun from the Ningbo Institute of Materials Technology and Engineering (NIMTE) at the Chinese Academy of Sciences has made significant strides in solar technology. They developed a new multifunctional cage-like diammonium chloride molecule that effectively reduces interfacial energy losses in perovskite/silicon tandem solar cells (TSCs). The findings, detailed in the journal Nature Communications, highlight the potential of this technology to enhance the efficiency and stability of solar energy systems.

Tandem solar cells are gaining attention in the photovoltaic industry due to their potential for ultra-high efficiency and cost-effectiveness. The theoretical efficiency limit for these cells is set at 45.1%, yet many challenges remain, particularly with wide-bandgap perovskite top cells. A notable hurdle has been the significant interfacial energy loss occurring at the perovskite/electron-selective contact interface.

To tackle this issue, the research team synthesized the innovative cage-like diammonium chloride molecule and incorporated it into the perovskite/C60 interface. This integration helps to reduce film defects and modulate the interfacial dipole, effectively minimizing energy losses. The results are promising: the team fabricated perovskite solar cells with a power conversion efficiency (PCE) of 22.6% for devices with a 0.1 cm² active area and 21.0% for those with a 1.21 cm² active area.

When these optimized perovskite cells were incorporated into a 1.0 cm² monolithic perovskite/silicon TSC, the tandem device achieved a remarkable PCE of 31.1%. This improvement not only demonstrates the potential for higher efficiency but also brings enhanced operational stability. The tandem device maintained 85% of its initial efficiency after 1,020 hours of continuous maximum power point tracking under ambient conditions.

By addressing the critical interface issue in tandem solar cells, this research paves the way for the ongoing development of efficient and stable perovskite-based photovoltaic technologies. The team’s innovative approach could significantly impact the future of solar energy, making it a more viable option for widespread use and contributing to global sustainability efforts.