Browsing by Author "Roopali Sharma"

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Controlled carbon dots mixing boosts perylene diimide dye for enhanced absorbance and white light emission: Finding application in optoelectronic devices
(Elsevier B.V., 2025) Karan Surana; Pratibha Pansari; Roopali Sharma; Bhaskar Bhattacharya; Saurabh S. Soni; Geeta Durga
The development of white light-emitting materials is of particular importance for backlights, lighting, and full-color visual display devices. This work successfully attempts to obtain white light by mixing blue-emitting carbon dots (C-Dots) and greenish-yellow-emitting valine functionalized perylene diimide (PDI) dye in an aqueous medium. The two components were mixed in a controlled manner using the host-guest approach, i.e. adding PDI dye to C-Dots and C-Dots to PDI dye for generating C-Dots-PDI composites. The optical characterization of C-Dots-PDI composites revealed intriguing results wherein the incremental addition of C-Dots to a fixed concentration of PDI dye resulted in an unexpected enhancement in the absorbance of the PDI dye. The optimized C-Dots-PDI composites exhibited pure white light emission (CIE coordinates = 0.33, 0.33) upon excitation at 370 nm. The mechanism involved in the interaction was evaluated using photoluminescence spectroscopy, transmission electron microscopy, and cyclic voltammetry measurement. Additionally, the C-Dots were investigated for their practical application as an invisible ink for transmitting secret messages. Finally, the white light-emitting composites were evaluated for their solid-state emission and also employed as sensitizers in dye-sensitized solar cells (DSSC), which revealed the superior performance of PDI as a host and C-Dots as a dopant. © 2025 Elsevier B.V.