The effects of Se/S ratio on the photoelectric properties of nitrogen -doped graphene quantum dots decorated CdSxSe1-x composites
In the work, CdSxSe1-x/N-GQDs composites were fabricated via a simple one-step hydrothermal process and their tunable composition, structure and photoelectric properties were characterized by various techniques. The photoelectric properties of CdSxSe1-x/N-GQDs could be adjusted by different Se/S ratios and tunable band-gaps. CdSxSe1-x/N-GQDs composites reached the optimal photocurrent response and the lowest interfacial impedance at the Se/S ratio of 0.75:0.25. Mott-Schottky plots and LSV spectra showed that the n-type CdS0.25Se0.75/N-GQDs presented a higher carrier density under light illumination. The excellent properties of the composites could be attributed to the mechanism involved in the excitation and electron-transfer process. On one hand, the band-gap of CdS0.25Se0.75/N-GQDs was narrowed, and more electrons were excited by the lower band-gap energy to promote a superior electron separation and transportation. On the other hand, N-GQDs acted as charge carriers and conductive way providers for electron-transfer instead of electron-hole recombination in the composites.
» Author: Yun Lei, Beibei Du, Peng Du, Yuncui Wu, Yongqin Wang, Can Li, Linhui Luo, Bingsuo Zou
This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement Nº 768737