Theoretical investigation of potential halide-based perovskites for sustainable and eco-friendly optoelectronic applications: A first-principles investigation.

Halide-based perovskites (ABX3, where A is an inorganic/organic cation, B a metal cation, and X a halogen anion) have emerged as promising materials for large-scale technological applications like solar cells, LEDs, photodetectors, and other optoelectronic devices due to their cost-effectiveness, tunability of optical and electronic properties [1-8]. Their high absorption ability, tunable bandgaps, low carrier effective masses, broad absorption spectra, high mobility, long charge diffusion lengths, and natural abundance are useful for several applications [9,10]. These materials can be fabricated easily into thin films and diverse nanostructures such as nanocrystals, nanorods, nanowires, and nanoparticles, making them promising alternatives to silicon-based technologies [10-14]. The rapid improvement of power conversion efficiency (~ 24%) of these materials especially for lead-based halides attracts the scientific community significantly to explore it further in more eco-friendly and sustainable configurations.

Even though these materials possess several advantages, the dependency on lead in many high- performance perovskites raise toxicity and environmental concerns. At the same time, their stability under environmental conditions remains a challenge. In response to these concerns, extensive research efforts have been directed toward developing lead-free perovskite alternatives. Consequently, several inorganic variants have emerged as promising candidates, offering enhanced thermal stability and a reduced ecological impact by avoiding toxicity [15-18]. Riaz et al. [18] demonstrated that RbSrCl3 and RbSrBr3 exhibit direct band gaps of 7.37 eV and 6.79 eV, respectively, with strong ultraviolet absorption, while Ajay et al. [15] reported an indirect band gap of 3.32 eV for RbSrI3, emphasizing halide-dependent optoelectronic tailoring. Motivated by this fact, our present study aims to employ first- principles density functional theory (DFT) to investigate the tunability of structural, electronic, mechanical, and optical properties of different unexplored inorganic variants such as RbSrBr3−xIx across varying halide concentrations avoiding lead toxicity and environmental concerns.

• Research Project