Halide-Driven Bandgap Engineering and SLME-Based Photovoltaic Performance of Ba3PX3 Compounds: A First-Principles Study
Peeyush Kumar Kamlesh1,*, Himanshi Sharma2, Shrikant Verma1, Ajay Singh Verma3,4, Reena Saxena5, Dinesh C. Sharma6
1 Department of Physics, Poornima University, Jaipur, Rajasthan, India
2 School of Basic & Applied Sciences, Nirwan University Jaipur, Jaipur, Rajasthan, India
3 Department of Allied Sciences, Graphic Era Deemed to be University, Dehradun, Uttarakhand, India
4 Department of Physics, University Centre for Research & Development, Chandigarh University, Mohali, Punjab, India
5 School of Applied Sciences, Suresh Gyan Vihar University, Jaipur, Rajasthan, India
6 Department of Physics, Mahatma Jyoti Rao Phoole University, Jaipur, Rajasthan, India
* Corresponding Author: Peeyush Kumar Kamlesh. Email: 
Computers, Materials & Continua https://doi.org/10.32604/cmc.2026.081382
Received 01 March 2026; Accepted 28 April 2026; Published online 12 May 2026
Abstract
In the present work, Ba
3PX
3 (X = F, Cl, Br, I) all-inorganic and lead-free halide compositions have been studied as possible replacements for hybrid perovskites using first-principles calculations. All the considered materials were found to exhibit direct band gaps at the Γ-point, decreasing from 2.37 eV (Ba
3PF
3) to 1.48 eV (Ba
3PI
3). The optical calculations reveal strong absorption in the visible and near-UV regions, with the static dielectric constants ranging from 2.75 to 4.35 in the halide series. All the compounds are mechanically stable and have tuneable ductility and stiffness properties. Lattice stability is confirmed by thermodynamic analysis in broad temperature ranges (0–900 K) and pressure ranges (0–10 GPa). The spectroscopic limit maximum efficiency (SLME), which is a theoretical screening parameter that represents an upper limit, has a value of 39.17% at 300 K for an absorber thickness of 1 μm, comparable to practical thin-film photovoltaic architectures. The findings identify strong trends in the stability of structures, optoelectronic properties, and photovoltaic characteristics within the Ba
3PX
3 family and rank Ba
3PBr
3 and Ba
3PI
3 among the most promising lead-free photovoltaic absorbers.
Keywords
Bandgap engineering; optical and dielectric response; elastic and thermodynamic stability; spectroscopic limited maximum efficiency; high-efficiency solar absorbers
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