A novel copper (II)-based hybrid perovskite with enhanced nonlinear optical and photovoltaic properties: synthesis, stability, and DFT insights

Organic–inorganic hybrid perovskites like MAPbI₃ have recently gained substantial attention in the optoelectronic and photovoltaic fields. Studying luminous properties has been continuously pursued due to their possible intentions in fluorescent light tubes, sensing, and light-emitting devices. However, lead’s stability and toxicity issues limit their commercial applications. Here, we offer [C₄H₉NH₂]₂[Cu₂I₄] (1), a novel lead-free hybrid copper-based compound with a three-dimensional structure that encompasses [Cu₂I₄]²⁻ clusters in the tetragonal space group P4bm. Because of its well-defined crystal size, compound 1 assures consistency, repeatability, and excellent stability, which is essential for long-term device performance. Furthermore, second harmonic generation (SHG) demonstrates exceptional nonlinear optical (NLO) capabilities, with an estimated quadratic NLO coefficient (⁽²⁾) of roughly 0.24 pm/V. Photoluminescence investigations show two unique emission peaks at 425 nm and 736 nm, together with an optical bandgap of about 2.91 eV. The Density Functional Theory (DFT) calculations are performed to study electronic band structure and to calculate the electronic density of a compound [C₄H₉NH₂]₂[Cu₂I₄]. Computed values exhibit strong concordance with experimental data. These combined features suggest that compound 1 is a promising candidate for NLO applications, solar cells, and other photovoltaic technologies.