Acid Solution Processed VO2-Based Composite Films with Enhanced Thermochromic Properties for Smart Windows

Abstract

As a typical thermochromic material, VO2 coatings can be applied to smart windows by modulating the transmission of near infrared (NIR) light via phase transition. However, the inherent undesirable luminous transmittance (Tlum) and solar modulation efficiency (ΔTsol) of pure VO2 impede its practical application. In order to solve this problem, the porous VO2 based composite film was prepared by magnetron sputtering and subsequent acid solution process with Zn2V2O7 particles used as a sacrificial template to create pores, which showed excellent Tlum (72.1%) and enhanced ΔTsol (10.7%) compared with pure VO2 film. It was demonstrated that the porous structure of the film caused by acid solution process could improve the Tlum obviously and the isolated VO2 nanoparticles presented strong localized surface plasmon resonance (LSPR) effects to enhance the ΔTsol. Therefore, this method will provide a facile way to prepare VO2 based films with excellent thermochromic performance and thus promote the application of the VO2 based films in smart windows.

Facile Solution Process of VO2 Film with Mesh Morphology for Enhanced Thermochromic Performance

“…Moreover, the three elements including Zn, V, and O are distributed uniformly on the film as shown in Figure 2c-e. The mesh morphology is similar to that of LBZA in the previous reports [37]. The related reaction for the formation of the LBZA nanostructure on the VO2 surface can be expressed as follows: Figure 3 shows the roughness of the VO2 film before (a) and after (b) the solution process, which exhibits a great difference.…”

“…In Figure 4b, the XPS spectrum of Zn 2p3/2 can be divided into three peaks at 1021.9 eV, 1022.6 eV, and 1025.3 eV, respectively, indicating that the Zn element in the obtained sample exhibits three states in different chemical environments. The peak at 1021.9 eV matches crystalline ZnO well, whose binding energy value of Zn 2p3/2 is 1021.9 ± 0.1 eV [37], suggesting that the sample includes some ZnO. The peak at 1025.3 eV corresponds to Zn 2+ in Zn(CH3COO)2•2H2O [39], indicating that Zn(CH3COO)2•2H2O likely exists in the sample.…”

“…In Figure 4d, the O 1s region can be also divided into three peaks at 534.0 eV, 532.0 eV, and 531.5 eV. The peak at 532.0 eV is ascribed to Zn-O-C=O [37] in LBZA while the 531.5 eV peak is ascribed to ZnO [44]. The 534.0 eV peak is related to O in the H2O of Zn(CH3COO)2•2H2O [45].…”

Smart thermally responsive perovskite materials: Thermo-chromic application and density function theory calculation

“… Materials Structure ΔT sol T lum Transition temprature Transition time Ref. VO 2 ZrO 2 /VO 2 /ZrO 2 10.20% 55.80% 68 °C – [ 42 ] VO 2 /ZnO 19.30% 55.90% ∼50 °C – [ 43 ] Zn 2 V 2 O 7 -VO 2 10.70% 72.10% 49 °C – [ 44 ] VO 2 -W dope /ZnO 15.31% 59.57% 37 °C – [ 45 ] Hydrogels PNIPAm 79.76% 82.79% 32 °C – [ 46 ] HPC 19.40% 91.30% – – [ 47 ] Perovskite MAPbI 3-x Br x 15% 25% ∼40 °C [ 48 ] MAPbI 3-x Cl x 23.70% 85.20% 40.1 °C ...…”

Fabrication and Optical Characterization of VO2-Based Thin Films Deposited on Practical Float Glass by Magnetron Sputtering and Professional Annealing

“…Near the critical point, the electrical and optical properties of VO 2 change by 2-5 orders of magnitude, and the infrared transmittance can change by 40-60% [1][2][3][4]. Therefore, VO 2 has garnered considerable research attention for preparing smart windows [5,6], optical switches [7], biomedical sensors [8], relaxation oscillator [9], and so on.…”