Solar power has long been a beacon of hope in our pursuit of clean energy. However, the road to sustainable, high-efficiency photovoltaics has been riddled with roadblocks such as toxicity and instability in widely used lead halide perovskites. Could we engineer a solar cell that delivers not just high performance, but also durability, stability and environmental safety?
That question led us to (Ca,Ba)ZrS3, a chalcogenide perovskite with immense promise. Unlike its lead-based counterparts, this material boasts strong thermal and chemical stability. More importantly, its bandgap can be finely tuned down to 1.26 eV with less than 2% calcium doping, placing it squarely within the Shockley-Queisser limit for optimal photovoltaic conversion.
For the first time, my research team at the Autonomous University of Querétaro explored an innovative idea of pairing (Ca,Ba)ZrS3 with next-generation inorganic spinel hole transport layers (HTLs). We integrated NiCo2O4, ZnCo2O4, CuCo2O4, and SrFe2O4 into solar cells and simulated their performance using SCAPS-1D.
Our work, published in Optical and Quantum Electronics, has significantly raised the power conversion efficiency (PCE) to an impressive rate of over 34% by meticulously engineering layer thickness, carrier concentration, and interface properties.
We observed depletion widths up to 0.4 µm, 0.5 µm, 0.6 µm, 0.7 µm, and 0.2 µm for NiCo2O4, ZnCo2O4, CuCo2O4, and SrFe2O4 based solar cells, improving the charge carrier generation within the solar cells.
In particular, SrFe2O4 based cells delivered a stellar 34.24% PCE with less energy deficit (~ 0.11 V), elevated JSC (~34.12 mA/cm2) and improved absorption (~ 42%) due to their superior recombination resistance, enhanced built-in potential and optimized band alignment.
We are particularly encouraged by the superior performance of spinel HTLs compared to conventional organic counterparts. The combination of low cost, widespread availability, ease of synthesis, low electrical resistivity, environmental friendliness, and exceptional thermal and photochemical stability makes them highly compatible with emerging chalcogenide absorbers.
Beyond efficiency, we found that interface engineering plays a critical role. By minimizing defect densities and achieving ideal conduction and valence band offsets, effectively blocked charge recombination pathways, while allowing seamless hole transport. This fine-tuned architecture proves that sustainable solar technologies can be both high-performing and scalable.
Our research marks a pivotal step toward developing non-toxic, stable, and highly efficient thin-film solar cells. As we continue refining material properties and device configurations, we believe (Ca,Ba)ZrS3 solar cells integrated with spinel HTLs will soon become a cornerstone of next-generation photovoltaics. The future of solar energy is being reshaped and we are honored to contribute to this promising transformation.
This story is part of Science X Dialog, where researchers can report findings from their published research articles. Visit this page for information about Science X Dialog and how to participate.
More information:
Eupsy Navis Vincent Mercy et al, Modeling of (Ca,Ba)ZrS3 solar cells with next-gen spinel hole transport layers via SCAPS-1D, Optical and Quantum Electronics (2025). DOI: 10.1007/s11082-025-08228-7
Bio:
Dr. Latha Marasamy is a Research Professor at the Faculty of Chemistry–Energy Science Program at UAQ, where she leads a dynamic team of international students and researchers. Her mission is to advance renewable energy, particularly in the development of second and third-generation solar cells, which include CdTe, CIGS, emerging chalcogenide perovskites, lead-free FASnI3 perovskites, quaternary chalcogenides of I2-II-IV-VI4, and hybrid solar cells. She is working with a range of materials such as CdTe, CIGSe, CdS, MOFs, FASnI3, graphitic carbon nitride, chalcogenide perovskites (ABX3, where A = Ba, Sr, Ca; B = Zr, Hf; X = S, Se), quaternary chalcogenides (I2-II-IV-VI4, where I = Cu, Ag; II = Ba, Sr, Co, Mn, Fe, Mg; IV = Sn, Ti; VI = S, Se), antimony based Sb2Se3, Sb2(S,Se3) and CuSb(S,Se)2, metal oxides, MXenes, ferrites, plasmonic metal nitrides, and borides for solar cell applications. Additionally, Dr. Marasamy is investigating the properties of novel materials and their influence on solar cell performance through SCAPS-1D simulations.
Citation:
Advancements in (Ca,Ba)ZrS₃ solar cells using innovative spinel hole transport layers (2025, May 22)
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