N, S double-doped GQDs intercalated nanoflower-like MoS2 as an efficient counter electrode catalyst for DSSCs

Abstract

Designing Pt-free counter electrode (CE) materials with good conductivity, stability and catalytic activity is essential for further development of dye-sensitized solar cells (DSSCs). In this paper, MoS 2 /graphene quantum dots (M/GQD) composites were successfully prepared by inserting GQDs into MoS 2 interlayers using one-step hydrothermal method and applied to the CEs of DSSCs. The results of density functional theory (DFT) calculations demonstrated the rationality of the structure of M/GQD, which has a stronger capacity to adsorb I atom. According to the electrochemical results, the M/GQD CEs exhibited excellent catalytic activity and charge transfer capability. The PCE of M/GQD-based DSSCs (5.79 % at 100 mW/cm 2 and 18.14 % for simulated indoor light at 1000 lux) was much higher than that of MoS 2 -based DSSCs (3.11 % and 10.23 %, respectively). The synergistic coupling of M/GQD results in abundant catalytic active sites, excellent conductivity and good stability, creating a promising channel for charge transfer. Overall, our work indicates that the introduction of GQDs provides a facile strategy for synthesizing efficient and stable CE materials. • N,S double-doped GQDs intercalated MoS 2 to enlarge the layer spacing. • Synergistic effect leads to improved electrical conductivity and catalytic activity. • Excellent PCE under both strong and low light irradiation. • The introduction of GQDs enhances the stability of MoS 2 .