http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/125 Wed, 12 Aug 2026 22:27:04 GMT 2026-08-12T22:27:04Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12859 Title: Polymer-Assisted Crystallization and Defect Passivation in Planar Wide-Bandgap FAPbBr3 Perovskite Solar Cells Authors: Amalraj, P.A.; Loheeswaran, S.; Landova, L.; Neykova, N.; Holovský, J. Abstract: Wide-bandgap lead bromide perovskites such as FAPbBr 3 are promising candidates for tandem solar cells and high-voltage optoelectronic applications, yet their performance is limited by surface and bulk defects that induce severe nonradiative recombination and limit stability. In this work, we present a defect passivation and crystallization control strategy by incorporating poly­(methyl methacrylate) (PMMA) into the antisolvent during FAPbBr 3 film fabrication. PMMA treatment leads to improved film morphology with larger grains, reduced surface roughness, and enhanced crystallinity. FTIR analysis reveals that the carbonyl groups in PMMA coordinate with undercoordinated Pb 2+ ions, effectively passivating electronic trap states. Photothermal deflection spectroscopy (PDS) shows reduced sub-bandgap absorption and lower Urbach energy, indicating suppressed deep-level defects and reduced energetic disorder. Enhanced photoluminescence intensity, prolonged carrier lifetimes, and decreased trap densities further confirm suppressed nonradiative recombination. As a result, PMMA treatment increases Voc by over 100 mV and improves power conversion efficiency by more than 1%, achieving a Voc of up to 1.510 V with reduced hysteresis and improved ambient stability. These findings demonstrate the effectiveness of polymer-assisted strategies for improving both efficiency and stability of wide-bandgap perovskite solar cells, offering a pathway toward high-voltage and tandem photovoltaic applications. Wed, 01 Jan 2025 00:00:00 GMT http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12859 2025-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12855 Title: Nickel oxide hole transport layer for perovskite solar cells: Preparation via pulsed laser deposition with simulation and experimental insights Authors: Amalraj, P.A.; Horynova, E.; Holovsky, J.; Landova, L.; Jain, N.; Pakki, A.D.; Kuo, M.H.; Pelikánová, I.B,; Dzurňák, B.; Horák, L.; Pop-Georgievski, O.; Neda, N. Abstract: Nickel oxide (NiOx) has gained attention as a promising inorganic hole transport layer for perovskite solar cells due to its wide bandgap, high transparency, and stability. However, tuning of band alignment by an extra dipole layer is necessary to achieve high efficiencies. Our predictive simulations suggest that NiOx bandgap tuning can also improve solar cell performance. Motivated by these findings, this study experimentally investigates NiOx films with different bandgap fabricated using pulsed laser deposition under varying deposition conditions, including oxygen pressure, substrate temperature and laser frequency. Our outcomes show that mainly the deposition temperature significantly influences the chemical composition, optical properties, and defect states in the NiOx films, lattice constants and morphology as confirmed by X-ray photoelectron spectroscopy, photothermal deflection spectroscopy, X-ray diffraction spectroscopy, atomic force microscopy and scanning electron microscopy. Experimentally, FA0.83Cs0.17Pb(I0.6Br0.4)3 mixed halide perovskite solar cells were fabricated on NiOx substrates prepared under varying oxygen pressures and pulse numbers, achieving a maximum power conversion efficiency of approximately 8 %. This demonstrates that NiOx deposited by pulsed laser deposition, when properly tuned, is a promising candidate for an efficient hole transport layer in perovskite-based photovoltaics. Wed, 01 Jan 2025 00:00:00 GMT http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12855 2025-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12854 Title: Synergetic effect of tetraoctylammonium chloride in suppressing photoinduced phase segregation in mixed halide perovskite solar cells Authors: Amalraj, P.A.; Rajavinayagam, A.; Landova, L.; Dopita, M.; Holovsky, J. Abstract: Phase segregation, caused by halide ion migration under illumination, is a critical challenge limiting the commercialization of mixed-halide perovskites. In this study, a facile and effective strategy is introduced to mitigate photoinduced phase segregation in the FA0.83Cs0.17Pb(I0.6Br0.4)3 mixed halide perovskite film by employing tetraoctylammonium chloride (TOAC) as both an additive and surface passivation for the first time. The results demonstrate that TOAC effectively reduces halide ion migration, stabilizes the perovskite phase, and suppresses phase segregation, particularly in the combined additive-passivation configuration. Mixed-halide perovskite solar cells fabricated with this dual TOAC approach achieve the highest efficiency of 15.8 %, with enhanced stability under continuous illumination and reduced hysteresis. The study highlights the critical role of TOAC in suppressing phase segregation, and improving the stability and performance of mixed-halide perovskite solar cells by addressing both surface and bulk defects, facilitating the development of more stable and efficient mixed-halide perovskite solar cells. Wed, 01 Jan 2025 00:00:00 GMT http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12854 2025-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12480 Title: Chundikulam National park: a review of its current status and future prospects Authors: Gajapathy, K.; Arthiyan, S.; Suvanthini, T.; Thirumayuran, T. Wed, 01 Jan 2025 00:00:00 GMT http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12480 2025-01-01T00:00:00Z