Understanding the Semi-Switchable Thermochromic Behavior of Mixed Halide Hybrid Perovskite Nanorods

Abstract

Intelligent regulation of solar irradiation and modulation of a window's thermo-optical properties can be achieved using thermochromic (TC) coatings. In this work, the semi-switchable TC property of a mixed halide hybrid perovskite, CH 3 NH 3 PbI 3−x Br x , has been thoroughly investigated from the bromine addition (x = 0, 1, 2, 3) perspective. Nanorods of composition CH 3 NH 3 PbIBr 2 (with x = 2) exhibit excellent TC behavior, and they are further explored as a TC coating material for smart window applications. An attempt has been made to establish the structure−property−performance relationship for a TC perovskite window, employing various physicochemical characterizations. The TC perovskite nanorods exhibit a significantly low-temperature transition thermochromism in the visible and ultraviolet region. TC properties are further improved in terms of visible light transmittance (T vis ) and solar modulation (T sol ). First-principles calculations involving density of states, crystal structure, band alignment, and thermochromic behavior interpretation of CH 3 NH 3 PbIBr 2 further confirm that effectively separating the crystal structure alignments once in contact with water drives its TC characteristics. Intriguingly, the perovskite smart window can reduce the indoor air temperature by about 50 °C when the outside temperature reaches 80 °C. This work's combined experimental and theoretical approach is clearly a preliminary attempt to develop and design strategies that seek to balance thermal and luminous spaces using glazing integrated nanostructured perovskite material systems.

Synergistic Effect of Paraffin-Incorporated In2O3/ZnO Multifold Smart Glazing Composite for the Self-Cleaning and Energy-Saving Built Environment

“…Equations 1 and 2 were employed to determine the luminous and solar transmission, respectively. 31 where T (λ) represents the transmittance value of the composite-coated glass at wavelength λ, and y (λ) corresponds to human eye’s photopic luminous efficiency designated by the International Commission on Illumination (CIE). All the related transmission measurements and analyses were investigated at 520 nm compared to CIE photopic luminous human eye efficiency.…”

Multi‐stimuli‐responsive and Multi‐functional Smart Windows

“…[170] Such reversible changes can in turn induce changes in color. Two-dimensional perovskites such as (C 6 H 4 (CH 2 NH 3 ) 2 )(CH 3 NH 3 ) nÀ 1 Pb n I 3n + 1 [171] and CH 3 NH 3 PbI 3À x Br x [172] can also function as humidity-sensitive thermochromic materials. The advantage of this system will be discussed in multi-functional smart windows.…”

Smart Glazing Thermal Comfort Improvement Through Near-Infrared Shielding Paraffin Incorporated Sno2-Al2o3 Composite

“…Temperature recording was carried out with the TC-08 thermocouple data logger (Pico Technology). The IR images were taken with a FLIR T425 camera positioned at a distance of 10 mm and then processed using corresponding software to prepare final images [38]. The viscosity measurement was performed on a Brookfield Ametek DVNext equipment.…”