Self-Powered Light-Directed Electrophoretic Deposition for Smart Windows
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Solution Overview
Problem
Existing window technologies, such as electronic shades and sun shades, rely on external power sources and have limited lifespan due to the use of liquid crystals, which degrade over time, and lack self-powered systems that can operate in open circuit conditions.
Innovation Solution
A self-powered, reversible light-directed electrophoretic deposition device with a photoconductive layer between two transparent sheets, where nanoparticles in a fluidic solution are attracted to illuminated areas without an external voltage, allowing for dynamic control of electric fields and reversible deposition on the photoconductive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electronic window shades or tinting are used to provide shading and cooling, then the shading and cooling function is achieved, but external power source and wiring are required which becomes problematic
Solution Approach 1:
The window coating system generates its own operating voltage through the photoelectric effect when exposed to light. The first sheet with photoconductive material acts as a photoelectric converter that produces electrical charge separation under illumination, creating the electric field needed for particle deposition without requiring external power sources or wiring. This self-powered mechanism eliminates the need for batteries, power cords, or complex electrical connections while maintaining the shading function.
Solution Approach 2:
The invention replaces the mechanical/electrical system of external power delivery with a photoelectric conversion system. Instead of using external batteries or power sources connected through wiring, the system uses the incident light itself to generate the electrical field through photoelectric effect in the photoconductive layer, substituting a light-driven electrochemical mechanism for traditional electrical power delivery.
2Stability of the object's composition
If smart window applications use applied bias to hold transparent state, then the transparent state is maintained, but power is required and windows default to opaque without power
Solution Approach 1:
The invention inverts the traditional smart window logic. Instead of requiring continuous power to maintain transparency (active transparent state), this system uses light exposure to create opacity through particle deposition, and returns to transparent when light is removed. The unstable charged state created by photoelectric effect drives particle accumulation on the illuminated surface, reversing the conventional approach where power maintains a stable transparent state.
Solution Approach 2:
The system changes the operational parameters from voltage-controlled transparency to light-controlled particle deposition. By varying the light exposure parameters (intensity, duration, pattern), the system controls the degree of particle accumulation on the photoconductive surface, thereby controlling the optical properties. This parameter change eliminates the need for continuous power application while achieving reversible transparency control.
3Use of energy by moving object
If photoelectrochemical devices are used to generate energy from light, then self-powered operation is achieved, but external circuits are required to move electrons
Solution Approach 1:
The invention extracts and eliminates the external circuit component from the photoelectrochemical system. Instead of using external wires and circuits to collect and transport electrons generated by the photoconductive material, the system uses the localized charge separation and electric field generation directly at the particle-coating interface. The electrons remain localized in the photoconductive layer, creating sufficient electric field for particle deposition without requiring electron extraction through external circuits.
4Use of energy by moving object
If liquid crystals are used in self-powered sun shade, then self-powered operation is achieved, but the crystals degrade over time and have limited life span
Solution Approach 1:
The invention replaces the fragile, degradable liquid crystal molecules with robust, stable inorganic components: a photoconductive oxide layer and suspended particles. These materials are chemically stable, resistant to degradation, and can withstand prolonged light exposure and electrical stress. The system uses stable metal oxides and particle suspensions instead of organic liquid crystals, dramatically extending the operational lifespan while maintaining self-powered functionality.
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
Enables energy-efficient, reversible shading and cooling without external power, reducing energy consumption and extending the lifespan of window components by using incident light to generate electric fields and deposit nanoparticles, allowing for patterned and tunable opacity.
Implementation Method 1
receiving light on a photoconductive layer of an electrophoretic deposition (EPD) device
Implementation Method 2
use incident light and photoconductors to generate electron-hole pairs and cause chemical reactions to generate energy
Implementation Method 3
electrophoretic deposition (EPD) device having a chamber defined by a first sheet, a second sheet and a spacer between the first and second sheets
Implementation Method 4
The particles in the solution are attracted from suspension to illuminated portions of the photoconductive layer
Data Source
AI summary
According to one embodiment, a method includes receiving light on a photoconductive layer of an electrophoretic deposition (EPD) device, the EPD device having a chamber defined by a first sheet, a second sheet and a spacer between the first and second sheets, where the first sheet is nonopaque and includes the photoconductive layer, where the second sheet is nonopaque and spaced from the first sheet, where a fluidic solution having a plurality of particles is in the chamber. The particles in the solution are attracted from suspension to illuminated portions of the photoconductive layer in the absence of an external voltage applied to the first and second sheets. The particles become deposited on the illuminated portions of the photoconductive layer.