This review article is devoted to the analysis and synthesis of results from electronic structure studies of lead-free double halide perovskites using Density Functional Theory (DFT) methods. In recent years, organic-inorganic perovskites have revolutionized the field of photovoltaics; however, their commercial application is hindered by high lead toxicity and phase instability. Replacing the lead ion with a combination of monovalent and trivalent cations to form a double perovskite structure (A₂B’B’’X₆) represents a promising solution to this problem. The paper comprehensively examines the methodological aspects of first-principles calculations, including the selection of exchange-correlation functionals (GGA-PBE, HSE06) and the inclusion of spin-orbit coupling necessary for the accurate description of systems containing heavy elements (e.g., bismuth). Key findings indicate that most well-known double halide perovskites, such as Cs₂AgBiBr₆ , possess an indirect bandgap, which limits their light-absorption efficiency. Mechanisms for bandgap engineering via halogen substitution and B-site doping are discussed. The theoretical significance of the work lies in the systematization of data regarding the nature of chemical bonds and band structure formation, where the valence band and conduction band are determined by the hybridization of halogen p-orbitals and metal d/p-orbitals. The practical significance of the study is demonstrated by justifying the use of computational modeling for the targeted search for new stable and environmentally safe materials for high-efficiency optoelectronic devices prior to expensive laboratory synthesis.

AIMAGANBETOVA Z.K.

PhD, associate professor, K. Zhubanov Aktobe regional university, Aktobe, Kazakhstan.

Е-mail: z.aimaganbetova@zhubanov.edu.kz, https://orcid.org/0000-0002-8765-516X

ZHANTURINA N.N.

PhD, associate professor, K. Zhubanov Aktobe regional university, Aktobe, Kazakhstan.

Е-mail: nzhanturina@zhubanov.edu.kz, https://orcid.org/0000-0001-9540-6334

KULSHYMBAYEV Y.A.

Master’s student, K. Zhubanov Aktobe regional university, Aktobe, Kazakhstan.

Е-mail: ekulsymbaev@gmail.com, https://orcid.org/0009-0002-7210-3394

 

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lead-free double halide perovskites, density functional theory, electronic structure, bandgap, optical properties, computational materials science, optoelectronics