Enhanced Photoelectrochromic Performance of WO3 Through MoS2 and GO–MoS2 Quantum Dot Doping for Self-Powered Smart Window Application

Abstract

Photoelectrochromic devices, which combine light-induced color change with energy-efficient optical modulation, have attracted significant attention for applications such as smart windows, displays, and optical sensors. However, achieving high optical modulation, fast switching speeds, and long-term stability remains a major challenge. In this study, we explore the structural and photoelectrochromic enhancements in tungsten oxide (WO3) films achieved by doping with molybdenum disulfide quantum dots (MoS2 QDs) and grapheneoxide–molybdenum disulfide quantum dots (GO–MoS2 QDs) for advanced photoelectrochromic devices. X-ray diffraction (XRD) analysis revealed that doping with MoS2 QDs and GO–MoS2 QDs leads to a reduction in the crystallite size of WO3, as evidenced by the broadening and decrease in peak intensity. Transmission Electron Microscopy (TEM) confirmed the presence of characteristic lattice fringes with interplanar spacings of 0.36 nm, 0.43 nm, and 0.34 nm, corresponding to the planes of WO3, MoS2, and graphene. Energy-Dispersive X-ray Spectroscopy (EDS) mapping indicated a uniform distribution of tungsten, oxygen, molybdenum, and sulfur, suggesting homogeneous doping throughout the WO3 matrix. Scanning Electron Microscopy (SEM) analysis showed a significant decrease in film thickness from 724.3 nm for pure WO3 to 578.8 nm for MoS2 QD-doped WO3 and 588.7 nm for GO–MoS2 QD-doped WO3, attributed to enhanced packing density and structural reorganization. These structural modifications are expected to enhance photoelectrochromic performance by improving charge transport and mechanical stability. Photoelectrochromic performance analysis showed a significant improvement in optical modulation upon incorporating MoS2 QDs and GO–MoS2 QDs into the WO3 matrix, achieving a coloration depth of 56.69% and 70.28% at 630 nm, respectively, within 10 min of 1.5 AM sun illumination, with more than 90% recovery of the initial transmittance within 7 h in dark conditions. Additionally, device stability was improved by the incorporation of GO–MoS2 QDs into the WO3 layer. The findings demonstrate that incorporating MoS2 QDs and GO–MoS2 QDs effectively modifies the structural properties of WO3, making it a promising material for high-performance photoelectrochromic applications.