How Is Smart Glass Film Made?

One item made with PDLC technology is the smart glass film. The sandwich layer structure is made up of PET film, ITO, and polymer-dispersed crystal.

The full name of ITO is Indium tin oxide (ITO), In2O3 • SnO2, whereas the entire name of PET is Polyethylene Glycol Terephthalate.

A technique that has become more common in modern homes and buildings is called smart glass, sometimes known as switchable glass. Modern homes and offices may be transformed into chic, contemporary spaces with this innovative alternative. Heat, light, and voltage are examples of external stimuli that can change the properties of smart glass, which is an electrochromic material. How to make smart glass film will be covered in this article.

Material

This smart glass film is manufactured using a unique process and consists of micron-sized liquid crystal droplets dispersed in a polymer matrix between two transparent film layers. Due to the disordered nature of the liquid crystal molecules within the droplet, the refractive index of the droplet is different from that of the matrix.

Both translucent and opalescent or opaque appearances are produced by the intense scattering of light at the rear droplet caused by the matrix. The optical axis of the liquid crystal droplet may be oriented to change the state of the disordered material from disordered to ordered by applying an electric field.

Transparency arises when the refractive indices are equal. Visibility results from the liquid crystal microdroplets returning to their astigmatic condition when the electric field is turned off.

Fundamental

Nematic liquid crystals in smart glass film systems are uniformly dispersed as micron-sized droplets inside a solid organic polymer matrix. Every droplet has a preferred orientation for its optical axis in the absence of voltage, but the orientation of every particle is disordered.

Application

Electrochromic materials, which change their optical properties in response to external stimuli, are used in this technique. It may be used on windows that are in place now or on other surfaces, such those in cars, buildings, and residences.

Electro-Optic Properties

The reaction of the smart glass film's optical qualities to an electrical current is known as its electro-optical characteristics. In its design, elements like as transmittance, voltage, reaction time, bevel length, contrast, and operational temperature range are crucial.

1. The Connection Between Voltage And Transmittance

Light transmission through a material is known as transmissance. Temperature has an impact on the relationship between voltage and transmittance. All PDLC films share the characteristic that at lower temperatures, a higher voltage is required for high transmittance. Furthermore, the T-V curve's hysteresis effect intensifies with decreasing temperature.

2. The Connection Between Slope Length And Transmittance

Slope length and transmittance are related to one other. Transmittance increases noticeably for wavelengths longer than 700 nm while the gadget is off. By increasing film thickness, adding dyes, and growing particle size, it is possible to reduce transmittance when off in the visible red and near-infrared spectrum. Increasing particle size increases total scattering area and decreases transmittance when the particle is in use, but increases the amount of scattered light when the particle's thickness is increased.

3. Time Of Response

Response time is the amount of time it takes for an opaque smart glass film to become transparent. The turn-off timings of thinner films vary according on temperature, from 50 ms to 600 ms. Light transmittance can be affected by the configuration of LC particles in low temperatures, and greater voltages can result in longer turn-off times.

The PDLC activation time is around 250ms at -10oC and is short at room temperature, with a starting voltage range of 60-100V. The activation period is inversely correlated with the square of the initial voltage, much like in conventional TN components. A thicker film increases activation voltage and decreases deactivation time regardless of temperature because the electric field in the film affects molecular alignment, and the electric field lessens with increasing film thickness.

4. Operating Temperature Range

The temperature range for operation relates to the dimmable glass film's normal function. DSC phase transition temperature measurement helps to understand how the polymer matrix affects the LC operating temperature range. 

Research suggests that LC should be dissolved in the polymer to act as a plasticizer. When LC is a mixture, one dissolved in the polymer affects the LC phase change. Similarly, the polymer prepolymer should be dissolved in the LC to act as an impurity and lower the LC phase transition temperature.

5. Contrast

The degree of difference between opaque and transparent states is called contrast, and is used to assess the properties of PDLC thin film optoelectronic materials.There are two ways to calculate contrast.

Using a diffuse light source, the first approach measures the standardized brightness in both the on and off modes. The type of light source that is used determines how successful this procedure is, thus during measurements, the light source must be specified.

The second method depends on the on and off states' spectral transmittance. If the measurement instruments' acceptance angles are constant, the outcomes of this approach may be compared between laboratories. Significant disparity.

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