To investigate the optical properties of the devices, the solar modulation efficiency (DTsol) was calculated to characterize the thermochromic smart window properties of the devices. Tvis denotes the integral visible transmittance of the devices. The calculated results of the three devices are shown in Table 1.These results indicate that the DT sol of the Ca is only 2.0%, and the Tvis values at high and low temperatures are 65.6% and 61.7%, respectively. The DTsol of Cb is 7.5%, which is much higher than Ca, and the Tvis values at high and low temperatures are 45.6% and 42.7%, respectively. The results suggest that the VO2-based core-shell-shell structure is beneficial for energy saving. For the Cc with a smooth VO2 thin film, the solar energy modulation ability of VO2 was maintained.