Chalcogenide perovskites are gaining attention as candidates for replacing lead halide perovskites owing to their excellent optoelectronic characteristics. Researchers from Mexico, Algeria and India have focused on lead-free chalcogenide perovskites, and BaZrS3 in particular, which is seen as an excellent alternative absorber due to its direct bandgap of approximately 1.7 eV, strong optical absorption and exceptional structural stability under diverse environmental conditions. Its naturally high p-type conductivity and earth-abundant elemental composition make it a sustainable and scalable solution for next-generation solar cells.
The BaZrS3-based chalcogenide perovskite solar cell architecture incorporating delafossite HTLs. Image from: Inorganic Chemistry Communications
Recognizing that the hole transport layer (HTL) plays a vital role in achieving high-efficiency and long-lasting photovoltaic devices, the team investigated the potential of inorganic delafossite HTLs, specifically CuFeO2, CuGaO2, and CuAlO2. These materials offer advantages over traditional organic HTLs like Spiro-OMeTAD, including lower cost, greater thermal and chemical stability, and favorable energy band alignment with BaZrS3.
Using the SCAPS-1D simulation tool, they performed a comprehensive theoretical study to optimize device parameters. Over multiple simulations, the scientists fine-tuned absorber acceptor densities, controlled defect concentrations, adjusted absorber thickness, and explored the influence of interfacial defect states at both the electron transport layer (ETL) and HTL junctions.
Advanced analysis methods, such as Nyquist plots, Mott-Schottky curves, and quantum efficiency studies, were applied to gain a detailed understanding of the charge transport dynamics and recombination behavior.
The team's findings demonstrate that through meticulous device engineering, BaZrS3-based chalcogenide perovskites can achieve significant performance gains.
The results indicate that careful engineering of BaZrS3-based devices with delafossite HTLs can yield impressive PCEs exceeding 28%, a milestone for lead-free solar technology. The devices integrated with CuFeO2 achieved a remarkable PCE of 28.35%, while CuGaO2 and CuAlO2 configurations attained 27.83% and 25.05%, respectively. Notably, these inorganic HTLs outperformed or matched Spiro-OMeTAD, underscoring their immense promise as robust, eco-friendly alternatives.
This work not only showcases the high potential of BaZrS3 as a non-toxic solar absorber but also provides the first comprehensive theoretical validation of delafossite HTLs within this material system. These findings provide insights for researchers and industry partners seeking to develop durable, scalable, and environmentally responsible photovoltaic devices for a sustainable energy future.
