Lead-free chalcogenide perovskites ABSe₃ show promise for high-efficiency solar cells

Lead halide perovskites have achieved remarkable power conversion efficiencies (PCE) of up to 26.1%. However, their instability against moisture and heat, along with toxicity concerns, limits their commercial viability. To address these challenges, we explored chalcogenide perovskites, specifically ABSe₃ (where A = Ca, Ba, and B = Zr, Hf), as promising alternatives.

These materials exhibit excellent optoelectronic properties, superior thermal and structural stability, and a non-toxic composition, making them ideal candidates for efficient, lead-free solar cells. The question now is, can they surpass the efficiency of conventional perovskites and redefine the future of solar energy?

For the first time, our research team at the Autonomous University of Querétaro in Mexico investigated the integration of CaZrSe₃, BaZrSe₃, CaHfSe₃ and BaHfSe₃ as absorber layers in solar cells. We optimized their performance using the Solar Cell Capacitance Simulator in One Dimension (SCAPS-1D), a computational tool developed by Mark Burgelman at the University of Ghent. This simulation allowed us to analyze the behavior of these materials under real-world conditions.

In our work published in Scientific Reports, we significantly enhanced device efficiency and ensured viability for practical applications by fine-tuning critical parameters such as carrier concentration, defect density, and absorber layer thickness.

Our approach led to improved light absorption, increased resistance to recombination, strengthened built-in potential, and minimized non-radiative recombination and charge transfer resistance. Additionally, our careful optimization enhanced the band alignment between each layer and improved the interface properties, resulting in remarkable increases in PCE.

Our simulations indicated that solar cells using CaZrSe₃ and BaZrSe₃ could exceed 30% PCE, a significant leap compared to conventional absorber materials. These improvements are attributed to enhanced short-circuit current density, increased quasi-Fermi level splitting, a higher carrier generation rate, elevated electric field strength, and larger quantum efficiency measurements, all of which contribute to superior efficiency.

Our research marks a crucial step toward the development of lead-free, high-performance solar absorbers. As part of our ongoing efforts, we aim to refine these materials further to ensure they are not only efficient but also scalable and cost-effective. By optimizing chalcogenide perovskites for photovoltaic applications, we contribute to the advancement of sustainable solar energy technologies.

In addition to improved efficiency, the integration of these materials has the potential to reduce production costs, enhance long-term operational stability, and provide a safer alternative to conventional perovskite solar cells. With continued experimental validation and further material optimization, chalcogenide perovskites could soon revolutionize the renewable energy sector, paving the way for a future powered by clean, reliable, and environmentally friendly solar technology.

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Dr. Latha Marasamy is a Research Professor at the Faculty of Chemistry at UAQ, where she leads an innovative team of international students and researchers. Her diverse research interests encompass carbon and graphene, chalcogenide semiconductors, metal oxides, MOFs, as well as plasmonic metal nitrides and phosphides, all aimed at energy and environmental applications. Additionally, her team provides theoretical insights into solar cells through the use of SCAPS-1D simulation.