Nanomaterials (NMs) with structural, optical, and dielectric properties are called functional or smart materials and have favorable applications in various fields of material science and nanotechnology. Pure and Co-doped MgAl₂O₄ were synthesized by using the sol-gel combustion method. A systematic investigation was carried out to understand the effects of the Co concentration on the crystalline phase, morphology, and optical and dielectric properties of Co-doped MgAl₂O₄. X-ray diffraction confirmed the cubic spinel structure with the Fd3̅m space group, and there was no impurity phase, while the surface morphology of the samples was investigated by scanning electron microscopy. The dielectric properties of the synthesized material are investigated using an LCR meter with respect to the variation in frequency (1-2 GHz), and their elemental composition has been examined through the energy-dispersive X-ray technique. The existence of the metal-oxygen Mg-Al-O bond has been confirmed by Fourier transform infrared spectroscopy. The value of the dielectric constant decreases with the increasing frequency and Co concentration. The optical behaviors of the Co²⁺-doped MgAl₂O₄ reveal that the optical properties were enhanced by increasing the cobalt concentration, which ultimately led to a narrower band gap, which make them exquisite and suitable for energy storage applications, especially for super capacitors. This work aims to focus on the effect of cobalt ions in different concentrations on structural, optical, and dielectric properties.

Perovskite crystals, nanocrystals, quantum dots (QDs), and two-dimensional (2D) materials are at the forefront of optoelectronics and quantum optics, offering groundbreaking potential for a wide range of applications, including photovoltaics, light-emitting devices, and quantum information technologies. Perovskite materials, with their remarkable, tunable bandgaps, high absorption coefficients, and efficient charge transport, have revolutionized the field of light-emitting diodes, photodetectors, and solar cells. QDs, owing to their size-dependent quantum confinement and high photoluminescence quantum yields, are crucial for applications in display technologies, imaging, and quantum computing. The synthesis of QDs from perovskite-based materials yields a significant enhancement in the performance of optoelectronics devices. Furthermore, 2D perovskites have recently exhibited extraordinary carrier mobility, strong light–matter interactions, and mechanical flexibility, making them highly attractive for next-generation optoelectronic applications. Additionally, this review discusses the synergistic potential of hybrid material architectures, where perovskite crystals, QDs, and 2D materials are combined to enhance optoelectronic performance and their role in quantum optics. By analyzing the effects of material structure, surface modifications, and fabrication techniques, this review provides a valuable resource for harnessing the transformative potential of these advanced materials in modern optoelectronic applications.