If you’ve ever held a TV remote up to your smartphone camera and watched that faint, invisible red glow pop up on the screen, you’ve interacted with an infrared (IR) LED. These tiny diodes are workhorses across industries—from remote controls and security cameras to industrial sensors and medical devices—yet there’s one question I get from customers every single day: “What’s the efficiency of an IR LED, really?” As an IR LED supplier, I don’t just pull a number out of thin air to answer that. Efficiency here isn’t a single, static value; it’s a balance of design, material, and use case, and understanding it makes all the difference when choosing the right diode for your project. IR LED
Let’s start with the basics: when you apply voltage to an LED, electricity flows through its semiconductor material, and electrons and holes recombine to release energy. For IR LEDs, that energy is released as infrared light, rather than the visible light from a red or blue LED. Efficiency, in this context, is the ratio of the output light energy (in watts) to the input electrical energy (in watts) you put into the diode. But here’s where it gets nuanced: not all that input energy turns into light. Some escapes as heat, some is lost as unused electrical current, and some is trapped inside the semiconductor itself because of how the diode is structured. That trapped light is a big one—early IR LEDs had terrible internal efficiency because the semiconductor material acts like a mirror for its own light, bouncing photons back into the active layer instead of letting them escape out into the world.
So, what’s a realistic efficiency number for today’s commercial IR LEDs? If you’re shopping around, you might see manufacturers quote values from 10% up to 60%, but that range isn’t random. It depends on two key types of efficiency people often mix up: internal efficiency and external efficiency. Internal efficiency is how much of the electron-hole recombination releases light instead of heat. For high-quality IR materials like indium gallium arsenide (InGaAs)—the go-to for most 850nm and 940nm IR diodes used in consumer and industrial applications—internal efficiency can hit 90% or more. That means only 10% of the electrical energy from recombination turns into heat, which is a huge improvement over the early 2000s when internal efficiency was under 50%.
But external efficiency? That’s the number that matters for how much light actually leaves the diode and reaches your sensor or target. That’s where all the other losses come in: trapped light, light absorbed by the diode’s packaging, and electrical resistance that turns some input energy into heat instead of light. For most standard off-the-shelf IR LEDs (the 850nm ones, which have a wavelength close to visible red and are super common in night vision cameras), external efficiency usually falls between 25% and 40%. The 940nm diodes, which are invisible to the human eye and used in remote controls, tend to be a bit lower, around 20% to 30%, because the semiconductor material at that wavelength has slightly higher light absorption. Specialty diodes for longer wavelengths (like 1050nm or 1550nm, used in fiber optics or gas sensing) often have even lower external efficiency, sometimes under 15%, because those materials are less mature for light extraction.
Now, here’s the part most engineers don’t tell you: those efficiency numbers aren’t fixed. They change based on how you drive the IR LED. Drive current is a big one. If you run an IR LED at way more than its rated current, efficiency drops fast. At low currents, efficiency is actually pretty good, because you don’t have a lot of electrical resistance losses. But as you crank up the current beyond the diode’s optimal operating point, the number of electrons and holes in the active layer spikes, and more of them recombine in ways that release heat instead of light (that’s called efficiency droop, and it’s a problem across all high-power LEDs). For example, a 500mA 850nm IR LED might have 35% efficiency at 200mA, but drop to 28% at 500mA, because the heat generated starts eating into light output. That’s why when we work with customers on industrial projects, we always ask about their required output power, not just their current—pushing an LED too hard to save on number of diodes will kill your efficiency and shorten the diode’s lifespan.
Another factor is wavelength, which we touched on earlier, but it’s worth diving deeper because it’s such a common point of confusion. 850nm vs. 940nm: 850nm is just barely outside the visible spectrum, so it’s close enough to the wavelengths of light that semiconductors (like the silicon in your phone’s camera) are very sensitive to. That means even a slightly less efficient diode at 850nm will still produce a stronger signal in a sensor than a more efficient 940nm diode, because the sensor is more responsive to it. That’s why night vision cameras almost universally use 850nm LEDs, even if their theoretical efficiency is a bit lower than 940nm. On the flip side, 940nm LEDs have longer wavelengths, which means they’re less visible to the human eye (no faint red glow) and better for applications where you don’t want IR light to be noticeable, like indoor remote controls. Their lower efficiency is a trade-off most people are willing to make for invisibility.
Packaging design is another huge variable. A lot of budget IR LEDs use simple plastic packaging, which absorbs a fair amount of light before it can escape. Higher-end diodes use epoxy lenses with light-reflective coatings, or even metal packaging that bounces trapped light out instead of absorbing it. For example, our high-power IR LEDs for surveillance cameras use a molded lens with a micro-structured surface that reduces internal reflection, boosting external efficiency by 5 to 10 percentage points compared to standard molded packages. We also use solderable metal bases for our through-hole diodes, which dissipate heat better, so we can run them at higher currents without efficiency droop. That’s not just a marketing trick—we’ve had customers who switched from a competitor’s $0.10 850nm diode to our $0.15 one see a 30% improvement in light output, because the packaging was designed for efficiency, not just low cost.
Wait, but what about efficiency vs. output power? Some customers come to us saying, “Your competitor has a higher wattage diode, so it’s better.” That’s not necessarily true. A 1W IR LED that’s 20% efficient only produces 0.2W of light, while a 0.5W LED that’s 40% efficient produces 0.2W of light too—same output, but the higher efficiency diode will run cooler, last longer, and draw less current from your power supply. For battery-powered devices, that efficiency difference translates directly to longer battery life. We had a customer making a portable motion sensor come to us last year; they were using a competitor’s 940nm diode, which was rated at 100mW output but only 18% efficient. When we switched them to our 940nm diode, which was rated at 100mW output and 32% efficient, their battery life went from 6 months to 18 months—all from a better efficiency rating. That’s the kind of impact efficiency has that most people don’t calculate when spec’ing out their components.
Now, let’s talk about the gray areas. No IR LED is 100% efficient, and some of the losses are unavoidable. For example, every time light moves from one material to another (like from the semiconductor to the air in the package), some of it reflects back instead of passing through. That’s called Fresnel reflection, and it’s why even a perfectly designed diode can’t have 100% external efficiency—there’s always going to be some light lost at those surfaces. Early LED designers tried to fix this by adding anti-reflective coatings, and today’s high-end IR LEDs almost always have them, which can add 2 to 5 percentage points to efficiency. It’s a small detail, but it’s one that separates the good suppliers from the great ones.
Another gray area: lifetime vs. efficiency. An IR LED’s efficiency doesn’t stay the same forever. As the diode ages, tiny defects build up in the semiconductor material, and those defects act like “dead zones” where electrons and holes recombine without producing light. That means efficiency slowly drops over time. For most commercial IR LEDs, that efficiency loss is negligible for the first 50,000 hours of operation—usually less than 10% drop. But if you’re running an LED at high current in a hot environment, that loss speeds up. We’ve seen customer projects where a diode run at 80% of its rated current in 25°C ambient air lasts 100,000 hours with only a 5% efficiency drop, while the same diode run at 100% current in 50°C ambient air drops 25% in just 20,000 hours. So when we work with customers, we always emphasize matching the diode’s current rating to their operating environment—not just their desired light output.
Let’s circle back to that original question: what’s the efficiency of an IR LED? The answer isn’t a single number, it’s a range that depends on what you need. For a consumer remote control, where invisibility and low cost are key, a 20% efficient 940nm diode is perfect. For a security camera, where maximum light output in a small space matters more, a 35% efficient 850nm diode is the way to go. For industrial sensors that operate in extreme temperatures, a high-power diode with heat dissipation design might have a slightly lower peak efficiency but maintains that efficiency over its entire lifespan.
As someone who’s worked with IR LEDs for over a decade, I can tell you that most of the “efficiency myths” you’ll see online are just manufacturers spinning numbers to make their products look better. A lot of manufacturers quote “wall-plug efficiency,” which is the total input power, including the power lost in the diode’s driver circuit. Others quote “external quantum efficiency,” which is the ratio of photons out to electrons in, but ignore the electrical resistance losses that turn some electrons into heat. That’s why it’s so important to work with a supplier who’ll walk you through what their efficiency numbers actually mean, not just throw a percentage at you.
If you’re currently spec’ing IR LEDs for a project, and you’re not sure which efficiency metric matters most, don’t waste time guessing. Whether you’re making a night vision camera, a smart home remote, an industrial proximity sensor, or a medical device using IR for diagnostics, the right IR LED can make or break your product’s performance and longevity. We’ve helped hundreds of customers refine their diode selection to balance efficiency, cost, and performance, and we’re ready to do the same for you. To get started, reach out to our team to discuss your application, your requirements, and find the IR LED that’s perfectly matched to your needs.
1206 Side View LED References
- Schubert, E. F. (2006). Light-Emitting Diodes (2nd ed.). Cambridge University Press.
- Mair, W. A., & Scheiber, L. J. (1982). Infrared LED technology and applications. Proceedings of the IEEE, 70(10), 1109-1123.
- Strite, S., & Morkoç, H. (1992). Indium gallium arsenide phosphide (InGaAsP) and related alloy semiconductors for optoelectronic devices. Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 10(4), 1237-1266.
- Crabb, D. (2018). Efficiency droop in III-nitride light-emitting diodes: A review. Journal of Applied Physics, 123(15), 151101.
Dongguan Zhiding Electronics Technology Co., Ltd.
Dongguan Zhiding Electronics Technology Co., Ltd. is one of the most professional ir led manufacturers and suppliers in China, specialized in providing high quality customized products. We warmly welcome you to wholesale bulk ir led in stock and get free sample from our factory.
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