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) coating implementation. In this work, the semiswitchable TC property of a mixed halide hybrid perovskite, CH3NH3PbI3-xBrx, has been thoroughly investigated from the bromine addition as x = 0, 1, 2, 3, perspective. The composition of CH3NH3PbIBr2 (when x = 2) nanorods exhibits excellent TC behavior, and further explores TC coating material for smart window application. An attempt has been forged to establish a structureproperty-performance relationship for a TC perovskite window, engaging various physicochemical characterizations. The TC perovskite nanorods exhibit a significantly lowtemperature transition thermochromism in the visible and ultraviolet region. TC properties further escalate in the visible light transmittance (Tvis) and solar modulation (Tsol). The first-principles calculations involving density of states, crystal structure, band alignment, and thermochromic behaviour interpretation of CH3NH3PbIBr2 further confirms effectively separating the crystal structure alignments once in contact with water driving their TC characteristics. Intriguing the perovskite smart window can anticipate reducing the indoor air temperature by about 50°C when the outside temperature reaches 80oC. This work's combined experimental and theoretical approach expressly offers a preliminary attempt to develop and design strategies that seek to balance thermal and luminous spaces served by glazing integrated nanostructured perovskite material systems.