Thermochromic Perovskite Windows with Ideal Transition Temperatures
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Solution Overview
Problem
Current thermochromic window technologies, particularly those using vanadium dioxide and metal halide perovskites, face challenges in achieving ideal critical transition temperatures and fast transition kinetics while maintaining low hysteresis and high solar modulation ability, which are essential for energy-efficient building applications.
Innovation Solution
A composition comprising a perovskite and a second phase with a salt and a switching molecule, such as water or methanol, that reversibly switches between opaque and transparent states within a critical temperature range of 20° C. to 95° C., optimizing the transition temperature and kinetics through the use of excess salt and polymers like polyacrylic acid, which interact with the perovskite to reduce activation energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If vanadium dioxide is used as a thermochromic material, then solar modulation ability is achieved, but the critical transition temperature is too high (68°C) for ideal window applications
Solution Approach 1:
The patent modifies the critical transition temperature of VO2 by incorporating it into a metal halide perovskite structure, changing the material's physical parameters to achieve a lower transition temperature (TC) within the ideal range of 10°C to 28°C while preserving solar modulation functionality
Solution Approach 2:
The invention creates a composite material system combining VO2 with metal halide perovskite (e.g., MAPbI3), where the perovskite matrix hosts the VO2 clusters, enabling synergistic properties of both materials including reduced transition temperature and maintained optical modulation capability
2Temperature
If the critical transition temperature is reduced below 68°C, then the material becomes more suitable for window applications, but transition kinetics slow down due to decreased thermodynamic driving force
Solution Approach 1:
The perovskite structure modifies the thermodynamic parameters of VO2, creating a new phase transition pathway that maintains fast kinetics even at reduced transition temperatures through altered crystal field effects and lattice dynamics
Solution Approach 2:
The patent utilizes the insulator-to-metal Mott transition of VO2 within the perovskite structure, where the confined geometry and electronic environment of the perovskite lattice enable rapid phase switching at lower temperatures through cooperative lattice-electron coupling
3Temperature
If the critical transition temperature is reduced, then a larger hysteresis width occurs due to the first-order phase transformation nature
Solution Approach 1:
The perovskite environment modifies the free energy landscape of the VO2 phase transition, reducing the energy barrier between phases and narrowing the hysteresis loop through changed electronic structure and lattice coupling
4Temperature
If metal halide perovskite is used for thermochromic windows, then ideal transition temperatures can be achieved, but the formation energy is inherently low leading to phase stability issues
Solution Approach 1:
The patent creates a composite where VO2 clusters are embedded within the perovskite structure, and the perovskite matrix itself is stabilized through specific composition design (e.g., mixed cations, halide composition) to prevent degradation while maintaining the desired transition temperature
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables thermochromic windows with improved energy efficiency by reducing the critical transition temperature to an ideal range, enhancing solar modulation, and maintaining rapid switching times, thus addressing the limitations of existing technologies.
Implementation Method 1
the perovskite undergoes a phase transformation from the opaque three-dimensionally coordinated perovskite phase to the transparent zero-dimensionally coordinated perovskite phase
Implementation Method 2
the composition is capable of reversibly switching between an opaque state and a transparent state... when the composition transitions through a critical temperature, Tc
Data Source
AI summary
The present disclosure relates to a composition that includes a first phase that includes a perovskite and a second phase that includes a salt, a polymer, and a switching molecule, where the first phase and the second phase are in physical contact, and the composition is capable of reversibly switching between a substantially opaque state and a substantially transparent state.