VO2/PNIPAm hybrid thermochromic material has been verified as promising to improve optical performance of smart windows. However, VO2 can be easily oxidized especially when being dispersed in the hydrogel matrix, and also the nonuniform dispersion of VO2 in a host will worsen the material’s optical performance. Herein, pure VO2(M)@SiO2 nanoparticles (NPs) were first prepared using a surfactant-free method. Then VO2(M)@SiO2/PNIPAm hybrid microgels were synthesized through suspension polymerization. The VO2(M)@SiO2 NPs in the hydrogel matrix exhibited obviously improved resistance to oxidation. Monodispersed hybrid microgel with uniformly distributed VO2(M)@SiO2 NPs (Sample I) was obtained. Meanwhile, compared with the best VO2 film reported, our composite microgel (Sample III) demonstrated a 164% increase in the solar modulating ability at a relatively high average luminous transmittance (38.4%). All these remarkable features of VO2(M)@SiO2/PNIPAm microgel synthesized in our work will help a lot in the practical application of the inorganic–organic hybrid nanothermochromic materials.
Zongxu Na,Xiao Liang,Hao Wang,Li Yu,Chunming Fan,Qian Wang,Xianbao Wang,Huai Yang
Smart photovoltaic windows (SPWs) are an emerging green technology presenting energy-saving by combining solar irradiance regulation and solar energy harvesting. The SPWs integrating extraordinary energy-saving performance, stable and controllable operational mode, and diverse functionality are essential for devising high efficiency energy-saving buildings (ESBs). However, the attainment of such features has yet to be realized in current iterations of SPWs. Herein, a conceptual demonstration of a split-type broadband modulation, self-driven, and self-cleaning SPWs is presented by coupling a silicon solar cell with a multifunctional chromogenic unit (MCU) for creating highly efficient ESBs. Within the multilayer structured MCU, thermal-responsive polymer stabilized liquid crystal (PSLC) and VO 2 @SiO 2 nanoparticles act as chromic component, enabling broadband light modulation. Thanks to the excellent electrothermal effect of indium tin oxide (ITO), the phase transition of PSLC and VO 2 @SiO 2 nanoparticles can be induced by the electrical power output generated by the silicon solar cell. Therefore, the transparency of SPWs can be manipulated according to the occupant's preference during the daytime. Moreover, a superhydrophobic SiO 2 coating provides SPWs with self-cleaning capability which effectively reduces water resource consumption and eliminates the inconvenience of window cleaning, while providing occupants with a clear view even in complex weather conditions.
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