Degradation of Thermoplastic Optics in LED Greenhouse Lighting
Recent research from Dow highlights a critical issue impacting the longevity and efficiency of LED lighting systems, particularly in demanding applications like greenhouses and outdoor illumination. A study evaluating commercially available LED lens clusters revealed that thermoplastic optics are susceptible to degradation over time, leading to discoloration and eventual failure.
Blue Light Photothermal Aging: The Core Issue
The research, detailed in Dow’s white paper “Blue Light Photothermal Aging of Thermoplastic and Silicone Lens Clusters,” focused on the effects of blue light photothermal aging on both silicone and thermoplastic optics composed of polycarbonate (PC), polymethyl methacrylate (PMMA), and high-temperature resistant PMMA (HT-PMMA).1 The study subjected lens clusters to stress conditions mirroring those experienced by optics in high-power LED luminaires.
Findings: Thermoplastics Show Significant Degradation
The principal finding indicates that most thermoplastic lens clusters tested exhibited discoloration over time, ultimately leading to catastrophic failure.1 While gradual degradation through discoloration is known to reduce light output, the study emphasizes that predicting catastrophic failure can be challenging and requires extended testing periods.
Implications for Greenhouse Lighting
This research is particularly relevant to the horticultural industry, where LED lighting is increasingly used to optimize plant growth and yields. As stated by Martijn Beukema, Technical Service & Development Scientist and Application Technology Leader for Lighting at Dow, the white paper’s findings are applicable to horticultural applications.1
Silicone Optics as a Reliable Alternative
Dow, a producer of moldable optical silicones under the SILASTIC™ brand, suggests silicone optics as a more reliable alternative. The company encourages luminaire manufacturers to consider this data when selecting optical materials during the design process to enhance product longevity and minimize the risk of failures.1
The Growing Importance of LED Longevity
The study arrives at a time of rapid growth in the global lighting industry, driven by the increased adoption of energy-efficient LED modules. Maintaining the longevity and light output efficiency of these modules is crucial, and the choice of optical materials plays a significant role in achieving this.
1 Beukema, Martijn and Van Tiggelen, Kevin. “Blue Light Photothermal Aging of Thermoplastic and Silicone Lens Clusters.” Dow, 2026. https://www.dow.com/en-us/market/mkt-electronics/sub-elec-lighting.html
Keep reading