How Luminescent Materials Are Different Than Filters

Filters

Luminescent materials, such as those used in luminescent films, can enhance the functionality of colored light filters, especially in advanced greenhouse lighting solutions. These filters work by selectively absorbing or transmitting certain wavelengths of light. They are composed of a material infused with pigments or dyes—potentially including luminescent compounds—that absorb specific wavelengths of light, allowing others to pass through. When integrated into greenhouse lighting, luminescent materials can modify the light spectrum in beneficial ways, potentially improving plant growth by optimizing the light that plants absorb.

The process involves the plant absorbing light and converting it into heat energy, which is then dissipated into the environment. This conversion is facilitated by the pigments or dyes in the filter, which may vibrate at frequencies similar to those of desired light wavelengths, such as red light. In some cases, luminescent materials can absorb light at one wavelength and re-emit it at another, further tailoring the light spectrum reaching the plants. As a result, the filter can be designed to transmit only specific wavelengths of light, like red light, which is crucial for photosynthesis.

The efficiency of this light conversion and the amount of light lost through a colored filter incorporating luminescent materials depend on several factors. These include the type, thickness, and the wavelengths of the filtered light, as well as the properties of the luminescent compounds used. Typically, the range of light loss through these filters is between 40-80%. However, the introduction of luminescent materials into the filters can potentially reduce this loss by converting non-useful wavelengths into those more beneficial for plant growth. The color intensity of the filter, influenced by the concentration of pigments, dyes, and luminescent materials, directly correlates with the amount of light intensity lost or transformed, offering an innovative approach to managing light in greenhouse environments for advanced agricultural applications.

For example, a deep red filter will absorb more light than a light pink filter. The thickness of the filter also plays a role in how much light intensity is lost. Thicker filters absorb more light than thinner filters, as they have a greater volume for the light to interact with.

The amount of light intensity lost is also influenced by the specific wavelengths of light being filtered. For example, if a green filter filters out blue light, less light intensity will be lost than if the same green filter is used to filter out red light, as green filters are less effective at absorbing red light.

It is important to note that while some light intensity is lost through a colored filter, the transmitted light’s quality (or color spectrum) is changed. For example, a blue filter will reduce overall light intensity but enhance the concentration of exposure to blue light in the spectrum, which can benefit specific applications such as plant growth or photography.

Figure 1. Filters absorb light and convert it to heat. Fluorophores absorb light and convert it to lower energy light or a redder color.

Luminescent Materials and Greenhouse Advanced Lighting Solutions

Luminescent materials, also known as fluorophores, are unique in their ability to emit light through processes such as fluorescence or phosphorescence. These materials stand out because when exposed to light, they absorb the energy and re-emit it at a longer wavelength (lower energy), which is why they’re often referred to as “glowing” materials or “light conversion materials.” This characteristic makes them invaluable in advanced lighting solutions, particularly in the context of greenhouses.

Innovative applications of luminescent materials, including luminescent films, in greenhouse coverings can significantly enhance light management. Quantum dots, dyes, and phosphors are examples of colored luminescent materials that can be integrated into these coverings. By doing so, it is possible to modify the spectrum of light that penetrates the greenhouse, which in turn can influence plant growth and development positively.

One of the groundbreaking applications of these materials is the use of quantum dots to fine-tune the sunlight’s spectral composition to meet the specific needs of various plants. By adjusting the size and composition of the quantum dots, their absorption and emission spectra can be tailored. This allows for the precise control over which wavelengths of light are absorbed and emitted, optimizing the light environment for enhanced plant growth.

For those interested in exploring the intricate relationship between light and plant growth, our blog, “Light Interaction with Plants: Reflection, Emission, and Absorption,” offers a deeper dive. It elucidates how luminescent materials, particularly luminescent films, are revolutionizing greenhouse advanced lighting solutions, heralding a new era of precision agriculture.