http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/125 2026-09-02T03:53:05Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12960 Title: Mitigation of Self-p-Doping and Off-Centering Effect in Tin Perovskite via Strontium Doping Authors: Frasca, C.; Alippi, P.; Schwiddessen, R.; Prashanthan, K.; Nasti, G.; Zuo, S.; Ur Rehman, M.O.; Aldamasy, M.H.; Hartono, N.T.P.; Musiienko, A.; Abate, A. Abstract: Tin-based perovskite solar cells offer a less toxic alternative to their lead-based counterparts. Despite their promising optoelectronic properties, their performances still lag behind, with the highest power conversion efficiencies reaching around 15%. This efficiency limitation arises primarily from electronic defects leading to self-p-doping and stereochemical activity of the Sn(II) ion, which distorts the atomic arrangement in the material. In this study, we investigate the effect of strontium doping in tin-based perovskite on the distortion of the material’s structure and its optoelectronic properties. Using a combination of Density Functional Theory calculations and experiments, we demonstrate that strontium doping reduces p-doping and structural strain. This approach improves the efficiency from 6.3% in undoped devices to 7.5% in doped devices without relying on dimethyl sulfoxide, a harmful solvent for tin-based perovskites. This method could enable precise control of tin off-centering and self-p-doping, advancing the development of efficient and stable tin perovskite solar cells. 2025-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12959 Title: Tailored Crystallization Dynamics for Efficient and Stable DMSO-Free Tin Perovskite Solar Cells Authors: Zuo, S.; Tarasov, A.; Frohloff, L.; Prashanthan, K.; Ruske, F.; Lounasvuori, M.; Frasca, C.; Dallmann, A.; Zu, F.; Mathies, F.; Scheler, F.; Hartono, N.T.P.; Guixiang, L.; Jinzhao, L.; Simmonds, M.; Wenhui, L.; Koch, N.; Albrecht, S.; Meng, L.; Unger, E.; Aldanmasy, M.H.; Musiienko, A.; Abate, A. Abstract: Tin perovskite solar cells are emerging as a sustainable lead-free alternative in thin film photovoltaics. DMSO-free processed tin perovskites are gaining interest due to the detrimental effects of DMSO on tin oxidation. However, replacing DMSO with other solvents remains challenging due to the accelerated crystallization dynamics in non-DMSO systems. In this study, the crystallization process in a DMSO-free solvent system is regulated by managing the transition from the sol-gel phase to the solid film. Specifically, piperazine dihydriodide (PDAI) and 4-tert-butylpyridine (tBP) are utilized to coordinately tune the colloidal chemistry through forming large pre-nucleation clusters in perovskite ink, further, facilitating the film formation process. By combining tBP and PDAI, a controllable crystallization rate is achieved as evidenced by in situ photoluminescence (PL) measurement during spin-coating. As a result, tin perovskite films show high crystallinity and improved microstructure. Devices treated with tBP+PDAI exhibit a champion power conversion efficiency of 7.8% and excellent stability without observable degradation for over 3000 h stored in the N2 glovebox. These findings advance understanding and managing crystallization in DMSO-free solvents processed tin perovskite solar cells. 2025-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12958 Title: Anthracnose of grapevines in Sri Lanka: Pathogen identification, epidemiological insights, and in vitro evaluation of bioactive extracts Authors: Sureshkumar, D.; Emmanuel, C.J.; De Costa, D.M. Abstract: Anthracnose disease of grapevines, historically attributed to Elsinoe ampelina, has emerged as a significant concern in the Jaffna Peninsula, Sri Lanka. This study aimed to characterize the disease’s etiology, epidemiology, and potential for biological control. Field assessments over two cultivation seasons (2022–2023) revealed a consistent pattern of disease progression, with peak incidence and severity occurring between 40 and 60 days post-pruning. Rainfall positively correlated with disease metrics, while wind speed showed a suppressive effect. Morphological and cultural characterization of 54 fungal isolates, coupled with multilocus phylogenetic analysis (ITS, actin, and histone H3), confirmed the presence of two distinct Colletotrichum morphotypes within the C. gloeosporioides species complex, potentially representing a novel lineage. Pathogenicity assays verified the virulence of representative isolates on grape leaves and fruits under both in vitro and in planta conditions. Furthermore, spore germination and lesion development were significantly inhibited by cell-free suspensions from Pseudomonas fluorescens, Bacillus megaterium, and ethanol extracts of Azadirachta indica, Lantana camara, Vitex negundo, Stoechospermum marginatum, and Padina boryana. These findings establish a members of new lineage of C. gloeosporioides complex as the primary causal agent of grape anthracnose in the region and highlight the promise of integrating biocontrol agents and botanical extracts into sustainable disease management programs. 2025-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12947 Title: Comparative Analysis of Qualitative and Quantitative Phytochemical Evaluation of Selected Leaves of Medicinal Plants in Jaffna, Sri Lanka Authors: Rajkumar, G.; Panambara, P.A.H.R.; Vinotha, S. Abstract: The traditional system of medicine in Sri Lanka has shown much better improvement, has fewer side effects, and is less expensive than modern synthetic drugs in the treatment of many diseases. The objective of the present study was to comparatively evaluate the qualitative and quantitative analysis of phytochemical constituents of leaves of Murraya koenigii (L.) Spreng., Tinospora cordifolia (Wild) Hook.f., Enicostemma axillare (Lam) A. Raynal, and Gymnema sylvestre R. Br. were collected from Jaffna District. The shade-dried leaves were powdered and extracted with ethanol using the cold extraction technique. These ethanolic extracts were subjected to phytochemical analysis using recommended laboratory techniques. The one-way analysis of variance (ANOVA) and Tukey's multiple comparisons at probability value (p <0.05) were used in the statistical analysis of the data. Phytochemical screening showed the presence of alkaloids, flavonoids, tannins, terpenoids, steroids, saponins, phenols, and glycosides. Murraya koenigii shows the highest phenol and alkaloid contents (1960.71±66.88 and 19.42±0.26). Enicostemma axillare shows the highest flavonoid and tannin contents (22.27±0.86 and 1.26±0.017). Therefore, E. axillare and M. koenigii can be used as nutraceuticals in traditional medicine. 2022-01-01T00:00:00Z