COMPUTATIONAL AND EXPERIMENTAL INVESTIGATION OF LEAD-FREE HALIDE PEROVSKITES FOR ENERGY HARVESTING AND OPTOELECTRONICS

Author

• Md Adil Hossain, University of Texas at TylerFollow

Abstract

The growing demand for sustainable energy has driven research into lead-free materials for mechanical and solar energy harvesting. Lead-free halide perovskites have emerged as promising alternatives due to their non-toxic nature, tunable electronic properties, and versatile optoelectronic performance, providing a pathway toward high-performance energy devices. To find a solution, this thesis presents a comprehensive investigation of lead-free, non-toxic halide perovskite materials for sustainable optoelectronic and mechanical energy-harvesting applications. By integrating first-principles density functional theory (DFT) calculations with experimental triboelectric nanogenerator (TENG) device fabrication, this work establishes structure-property-performance relationships in halide-engineered perovskite systems.

This thesis first describes the experimental design and fabrication of lead-free triboelectric nanogenerators (TENGs) based on perovskite-polymer composites. Initially, FASnCl₃@PVDF TENGs were fabricated and characterized, achieving an open-circuit voltage (V_OC) of 81.22 Vp-p, a short-circuit current (I_SC) of 11.29 μAp-p at an optimal excitation frequency of 15 Hz. To further enhance performance, bromine was partially incorporated into FASnCl₃ to form FASnBr_0.75Cl_2.25@PVDF, which exhibited significantly improved outputs: V_OC = 131.33 Vp-p, I_SC = 12.9 μAp-p, and a power density of 16.25 µW/cm². The improvement is attributed to Br incorporation, which created microvoids acting as charge-trapping centers, increased the effective contact area, and reduced the band gap, enhancing charge retention and carrier transport. Practical applications were demonstrated through human motion energy harvesting. The harvested energy was successfully stored in commercial capacitors, sufficient to power LED lights, demonstrating the device’s potential for wearable electronics and self-powered sensors.

The thesis also investigates lead-free Ca₃BiX₃ (X = F, Cl, Br, I) perovskites using first-principles DFT to evaluate their potential for optoelectronic applications. Structural optimization confirmed cubic Pm-3m (221) symmetry with lattice parameters increasing from 5.72 Å (Ca3BiF₃) to 6.42 Å (Ca₃BiI₃), reflecting halide ionic size effects. Dynamic stability was validated via phonon dispersion, while thermodynamic assessments of Gibbs free energy and formation enthalpy confirmed mechanical robustness. Electronic structure analysis using GGA-PBE and HSE06 functionals revealed direct band gaps decreasing from 3.18 eV to 2.39 eV, demonstrating tunable optoelectronic properties via halide substitution. Optical properties, including absorption coefficients, refractive indices, and dielectric functions, indicate strong UV and moderate visible-light response, suitable for solar and optoelectronic devices. Mechanical and thermal analyses confirmed structural stability and high-temperature resilience despite intrinsic brittleness. Collectively, these results identify Ca₃BiX₃ as a versatile, tunable, lead-free perovskite family for next-generation optoelectronic technologies.

The second DFT study examined Cs₂NaMoI₆ as a novel lead-free double-halide perovskite. The compound exhibited cubic Fm-3m symmetry, an optimized lattice constant of 12.03 Å, a Goldschmidt tolerance factor of 0.94, and a negative formation enthalpy of -2.31 eV, confirming its structural and thermodynamic stability. The calculated direct band gap of 1.11 eV suggests strong relevance for solar-energy conversion, while density of states analysis indicated dominant Mo- and I-orbital contributions near the band edges. Its optical response over 0–15 eV showed moderate visible-region absorption, significant optical conductivity, broad photon sensitivity, and low visible-region energy loss. Elastic constant analysis confirmed mechanical stability, with Pugh’s ratio and Poisson’s ratio indicating brittle behavior and sufficient strain accommodation for device-level applications.

Overall, this thesis demonstrates that halide-engineered lead-free perovskites can serve as versatile and sustainable materials for both optoelectronic and energy-harvesting technologies. The computational studies provide predictive guidance for designing stable perovskites with favorable electronic, optical, mechanical, and thermal properties, while the experimental study validates the device-level potential of perovskite composites. These findings contribute to the development of environmentally benign perovskite materials for renewable energy conversion, flexible electronics, wearable sensors, and next-generation self-powered systems.

Date of publication

Summer 7-28-2026

Document Type

Thesis

Language

english

Persistent identifier

http://hdl.handle.net/10950/5118

Committee members

Dr. Md Masud Rana, Dr. Premananda Indic, Dr. Shawana Tabassum

Degree

Master's in Electrical Engineering

Recommended Citation

Hossain, Md Adil, "COMPUTATIONAL AND EXPERIMENTAL INVESTIGATION OF LEAD-FREE HALIDE PEROVSKITES FOR ENERGY HARVESTING AND OPTOELECTRONICS" (2026). Electrical Engineering Theses. Paper 73.
http://hdl.handle.net/10950/5118