Insight into NaSiCl3: A Lead-Free Perovskite for the Next Generation Revealed by DFT and SCAPS-1D

Abstract

This study theoretically explores the potential of lead-free NaSiCl3, a chloride-based perovskite, as a photovoltaic absorber. Using density functional theory (DFT) calculations via WIEN2k and CASTEP, alongside SCAPS-1D simulations, we assess the material’s suitability from both atomic and device perspectives. The results confirm that NaSiCl3 is structurally, thermodynamically, dynamically (via phonon dispersion), and mechanically stable. Detailed electronic, optical, and thermoelectric analyses further support its promise for optoelectronic applications. NaSiCl3 exhibits an indirect bandgap of 0.869 eV (PBE-GGA+TB-mBJ) and 1.307 eV (HSE06), with the latter aligning well with optimal values for efficient solar energy harvesting. The broad absorption range across the infrared and visible spectrum, combined with favorable optical constants, highlights its potential as a solar absorber. Furthermore, thermoelectric evaluations reveal strong performance at elevated temperatures, expanding its utility in high-temperature optoelectronic devices. Based on these DFT insights, a planar n-i-p perovskite solar cell incorporating NaSiCl3 was modeled in SCAPS-1D. Among the eight tested architectures, the FTO/SnS/NaSiCl3/Zn3P2/Ni configuration yielded a maximum power conversion efficiency of 27.11%. These findings not only establish NaSiCl3 as a highly promising, lead-free perovskite for next-generation solar cells but also provide a strong theoretical basis to guide future experimental synthesis and device fabrication.