Er-doped carbon dots broadening light absorption range and accelerating electron transport for enhancing photovoltaic performance of CdS quantum dots sensitized cells

Abstract

In this paper, Er-doped carbon quantum dots (Er-CQDs) is first incorporated into CdS quantum dot sensitized solar cells (QDSSCs) for broadening light absorption range and accelerating electron transport. Er-CQDs are prepared by hydrothermal method forming Er-CQDs/TiO2 film. The CdS quantum dots (QDs) are deposited on Er-CQDs/TiO2 film by successive ionic layer adsorption and reaction (SILAR) method, constituting CdS/Er-CQDs/TiO2 photoanode. The structural and optical properties of the CQDs and CdS/Er-CQDs/TiO2 photoanode are characterized by FT-IR, UV–vis, FL and PL techniques. The composition and morphology are confirmed by XRD, EDX, SEM and TEM techniques. The optical properties of the influence of Er-CQDs on photovoltaic performance of CdS QDSSCs is studied by electrochemical methods. The experiment data show that the photovoltaic performance of CdS/Er-CQDs/TiO2 working electrode can greatly be enhanced compared that of CdS/TiO2. In comparison, the PCE increases from 0.34% of CdS/TiO2 device to 0.43% of CdS/CQDs/TiO2 device, whose escalating rate is 26.45%. Furthermore, the PCE increases from 0.34% of CdS/TiO2 device to 0.59% of CdS/Er-CQDs/TiO2 device, whose escalating rate reaches 73.53%.