R RAHIMI KAKOLAKI - School of Chemical Engineering, College of Engineering, University of Tehran, Tehran, Iran
SH FATEMI - School of Chemical Engineering, College of Engineering, University of Tehran, Tehran, Iran
F Talatori - School of Chemical Engineering, College of Engineering, University of Tehran, Tehran, Iran
M Fakheri - School of Chemical Engineering, College of Engineering, University of Tehran, Tehran, Iran

In this research, nitrogen doped carbon quantum dots (N-CQDs) were synthesized through pyrolysis using monoethanolamine (MEA) and citric acid. The impact of Thiourea (TH), as the source of sulfur, was investigated on the optical properties of synthesized CQDs. Synthesized CQDs were characterized by using FTIR analysis and optical properties were investigated by UV-Visible and PL Spectroscopy. The results revealed that N-CQDs and N,S-CQDs have the absorption edge of ۴۹۰ and ۵۱۵ nm, respectively. In addition, excitation - dependent emission was observed in synthesized CQDs through PL analysis. Photoelectrical measurements revealed improvement in efficiency of the fabricated solar cells using synthesized N,S-CQDs/TiO۲ compared to the as prepared TiO۲ solar cell. The results showed an improved efficiency with respect to the short-circuit current density and fill factor from ۰.۰۱۷ to ۰.۲۷ mA/cm۲ and from ۰.۴۷ to ۰.۶۶, respectively.

Carbon quantum dots, Quantum dots-sensitized solar cell, Nitrogen doped CQD, Sulfur doped CQD.