Nesamony Memorial Christian College

Quasi-two-dimensional (quasi-2D) perovskites have emerged as promising materials for next-generation photovoltaic technologies owing to their ability to combine high power-conversion efficiency with improved environmental stability compared with conventional three-dimensional (3D) perovskites. The incorporation of bulky organic spacer cations into layered perovskite frameworks introduces unique structural and optoelectronic characteristics that strongly influence carrier transport, defect formation, phase distribution, and operational durability. Recent advances have demonstrated that structural engineering strategies, including spacer-cation modulation, phase regulation, crystal-orientation control, additive engineering, and interface passivation, can significantly enhance photovoltaic performance while mitigating moisture-induced degradation, ion migration, and thermal instability. This review critically discusses the structural features, charge-transport mechanisms, and stability enhancement approaches in quasi-2D perovskite solar cells. Particular emphasis is placed on the relationships among layered crystal architectures, mixed-phase distributions, anisotropic carrier transport, and interfacial recombination behavior. Recent progress in device engineering, tandem photovoltaics, flexible solar cells, and scalable fabrication strategies is also summarized, together with the remaining challenges associated with phase heterogeneity, transport limitations, reproducibility, and long-term operational stability. Finally, future research directions involving multifunctional spacer molecules, advanced interface engineering, operando characterization techniques, and scalable photovoltaic integration are highlighted. This review provides a comprehensive perspective on the development of stable and high-efficiency quasi-2D perovskite solar cells for next-generation photovoltaic applications.

Metal-oxide nanocomposites have emerged as a versatile class of materials whose combined physicochemical characteristics are superior to those limitations of individual metal oxides. These hybrid materials demonstrate increased surface activity, synergistic electrical interactions, and improved structural stability properties which are crucial for next-generation energy, environmental, and sensing technologies by combining two or more nanoscale oxides into a nanocomposite. In this work, a nanocomposite SnO2/NiO was synthesized through co-precipitation method to achieve uniform particle dispersion and intimate interfacial contact between the constituent oxides. The successful creation of nanoscale domains with average crystallite sizes of 13.9 nm is confirmed by thorough structural analysis. The functional groups are identified using FTIR. Its morphology was described using SEM and HRTEM, and the elemental investigations was done using Energy Dispersive X-rays (EDAX) and XPS. The synthesized SnO2/NiO nanocomposite exhibited higher specific capacitance of 550 Fg−1 at 1 Ag−1. The material showed 90.25

The present research focuses on preparation and characterization of nano-coated heat transfer medium. It also focuses on its utilization and subsequent performance evaluation in half-cylindrical solar greenhouse dryer. The carbon nano tube and nano silicon carbide (CNT- nano SiC) coated heat transfer medium was successfully prepared by spray coating method. The ratio of CNT- nano SiC was optimized to be in 70:30 mass ratios and it provided the maximum coating efficiency of 83.9

Cytosinium dichloroacetate (CDCA) single crystal was grown using the slow evaporation technique at room temperature, and its crystal structure was determined by SXRD study. The stability and packing of the crystal are governed by strong N–H…O interactions as well as weaker C–H…O, C–H…Cl interactions. This work reports the structural, vibrational, optical, and third-order nonlinear optical investigation of cytosinium dichloroacetate single crystal for the first time. The experimental values were compared with theoretical values by density functional theory. NBO analysis provides insight into the existence of hydrogen bonding interactions present in the CDCA molecule. All the functional groups in cytosinium dichloroacetate were identified using FT-IR and FT-Raman analysis. UV–Visible study of CDCA reveals good optical transmittance, and the green light emission of CDCA was understood through fluorescence analysis. The thermal stability of CDCA up to 196 ℃ was confirmed by TG/DTA analysis. The third-order susceptibility (2.366 × 10–6 esu) and optical lower cut-off wavelength (291 nm) indicate an enhanced third-order nonlinear optical response when compared to reported similar crystals indicating the potential of CDCA for third-order nonlinear optical applications.

The novel organic single crystal 4-Bromoaniline hydrogen malonate (4-BRMAL) was grown using methanol with slow evaporation method. The crystal was analysed using UV-Vis, FT-IR, FT-Raman spectra and single-crystal diffraction. Theoretical calculations were performed using density functional theory (DFT) with the B3LYP/ 6-31G(d, p) basis set. These studies were aimed to investigate the molecular structure and vibrational frequencies of 4-BRMAL. Natural bond orbital (NBO) and natural charge analysis (NCA) have provided a detailed evaluation of the compound's stability by confirming the presence of both intra and intermolecular interactions. UV-visible spectroscopy revealed electronic transitions with a lower cut-off wavelength of 263 nm, while fluorescence spectroscopy demonstrated yellow and an orange emission spectra at 591 nm, indicating its potential for NLO applications. TG/DTA showed thermal stability up to 149.80 degrees C with significant weight loss of 4-BRMAL. Hirshfeld surface analysis and two-dimensional fingerprint plots identified key atomic interactions in the crystal packing. The frontier molecular analysis showed a 4.78 eV energy gap indicating significant charge transfer characteristics. Electron-hole distribution, interatomic interaction (IRI) and atoms in molecule (AIM) analysis revealed strong hydrogen bonding and electron delocalization confirming the compound's favorable electronic structure. Density of states (DOS) analysis further highlighted the potential for non-linear optical (NLO) applications. Theoretical NLO calculations indicated a second-order hyperpolarizability of 561.33 x 10-30 e.s.u, demonstrating 4-BRMAL's suitability for optoelectronic device applications. Z-scan analysis confirmed that 4-BRMAL is a promising potential candidate for NLO activity with a third-order hyperpolarizability of 6.05 x 10-6 e.s.u. These analyses suggest that the title compound 4-BRMAL is a promising candidate for optoelectronics and NLO devices.