Microwave-Assisted Green Synthesis of Citric Acid-Urea Carbon Dots as Potential Solar Cell Additives

Nitrogen-doped carbon dots (N-CDs) have attracted considerable attention owing to their unique physicochemical and optoelectronic properties, as well as their promising potential for energy-related applications. However, only a limited number of studies have systematically investigated the influence of microwave-assisted synthesis conditions on the formation of these nanomaterials. In this work, five different N-CDs samples were synthesized from the same precursor system, consisting of citric acid and urea, by varying the microwave irradiation power and exposure time. The effects of these synthesis parameters on the formation and physicochemical characteristics of the carbon dots were systematically investigated. The synthesized materials were comprehensively characterized by ATR-FTIR, SEM, XPS, TG-DTA, UV-Vis absorption spectroscopy, photoluminescence spectroscopy, and electrochemical analyses. All samples exhibited similar chemical compositions and surface functional groups, while variations in the synthesis conditions led to noticeable differences in their thermal behavior, optical properties, and electrochemical responses. These findings highlight the important role of microwave synthesis parameters in fine-tuning the physicochemical properties of N-CDs and contribute to a deeper understanding of the relationship between synthesis conditions and the resulting material characteristics. The materials obtained were preliminarily tested as additives in the photoactive layer of perovskite solar cells. Overall, this study provides useful insights for the design and optimization of carbon dots with properties tailored for specific applications.