Phase-Changing Polymer Film Smart Window With Broadband Opacity Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing smart windows technologies, such as photochromic, electrochromic, and thermochromic materials, suffer from limited bandwidth modulation, durability issues, and high costs for large-area applications, particularly in buildings, necessitating improved methods for tunable opacity and energy efficiency.
Innovation Solution
A smart window comprising a solid polymer film with a phase-changing moiety that transitions from opaque to transparent with controlled temperature, using a transparent heater and conductive layer for Joule heating, without metal/metal oxides or liquid crystals, enabling large light modulation over the whole solar spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If photochromic or electrochromic materials are used for smart windows, then the window can regulate light transmittance, but the bandwidth modulation is limited as the absorption spectra do not cover a broad range of wavelengths
Solution Approach 1:
The patent uses thermochromic materials that change their optical properties through temperature-induced phase transitions, allowing the absorption spectra to shift across a broad range of wavelengths. By controlling the transition temperature and using composite materials with different thermal responses, the system achieves wide bandwidth modulation from visible to infrared regions, overcoming the fixed absorption spectra limitation of photochromic and electrochromic materials.
2Adaptability or versatility
If thermochromic materials like hydrogels are used, then wider bandwidth modulation is achieved, but water leak and evaporation occurs in long duration operation
Solution Approach 1:
The patent employs ionic gels with specifically engineered local properties - using solid electrolytes and ion-conductive polymers that provide the necessary ionic mobility for thermochromic response while eliminating the free water content that causes leakage and evaporation. The local composition is optimized to maintain gel structure integrity over long durations, achieving both wide bandwidth modulation and improved reliability.
3Reliability
If ionic gels are introduced to replace hydrogels, then water-related issues are reduced, but the polymer matrix degrades over time due to ion introduction
Solution Approach 1:
The patent uses composite material systems combining ion-conductive polymers with stabilizing additives and crosslinked network structures. The composite formulation includes antioxidants, UV absorbers, and strategically placed crosslinks that protect the polymer matrix from ion-induced degradation while maintaining ionic conductivity for thermochromic function, thereby extending the operational lifetime.
4Ease of operation
If PDLC smart windows are used, then light transmittance can be regulated, but the bandwidth is limited due to fixed pitches
Solution Approach 1:
The patent employs thermochromic materials with dynamically adjustable transition temperatures through compositional control and external stimuli. Unlike the fixed pitch structures of PDLC, the thermochromic system can continuously adjust its optical response across different wavelength ranges by modifying the thermal environment or material composition, providing dynamic bandwidth adaptation while maintaining ease of operation through passive or active thermal control.
5Adaptability or versatility
If cholesteric liquid crystals with various pitches are used to expand switchable bandwidth, then the bandwidth can be increased, but the cost becomes prohibitive for large area applications
Solution Approach 1:
The patent achieves wide switchable bandwidth using thermochromic materials where the optical properties are controlled by temperature parameters rather than complex multi-pitch liquid crystal structures. This parameter-based control approach uses simple, scalable materials that can be manufactured at low cost for large areas, eliminating the need for expensive cholesteric liquid crystal assemblies while maintaining broad spectral modulation capability.
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 smart window achieves high luminous and solar transmittance modulation, with transparency maintained by consistent voltage, and opacity reversible through heating, outperforming existing thermochromic windows with over 500 cycles of switching.
Implementation Method 1
The transparent heater can be heated by applying voltage between two separate locations of the conductive layer
Implementation Method 2
A smart window comprising a solid polymer film with a phase-changing moiety that transitions from opaque to transparent with controlled temperature
Data Source
AI summary
A smart window including a solid polymer film which is opaque at an ambient temperature and transparent at an elevated temperature; a transparent heater to supply uniform heating to at least a part of the solid polymer film; and a power supply connected to the transparent heater.