लैंपशेड से ऊर्जा: अतिरिक्त समय तक काम करने वाला प्रकाश

Dr. Sudip Karmakar     
SCDD, CSIR

Think only sunlight can make solar power? Think again. Your home lighting could soon become a clean, constant source of energy.

Walk into your living room, turn on the light, and you're not just illuminating your room, you might be contributing to store energy for the future. We are used to thinking of solar energy as something that happens only outside where sunlight hits rooftop solar panels, and it converts the sunlight into usable electricity. But what if we told you that the light already illuminating your room could also power your gadgets? Step into the world of indoor light harvesting, a promising, eco-friendly technology that’s set to energize everything from smart thermostats to health trackers, all by soaking energy from the lights already around us.

Indoor Light Harvesting

Unlike traditional solar panels that works in sunlight, indoor light harvesters are built to function under artificial lighting like LEDs, fluorescents, and even old-school bulbs. The key is specialized photovoltaic materials that are tuned for converting low-intensity, diffuse light into electricity. These devices don’t need direct sunshine to function but a gentle glow is enough. Dye-sensitized solar cells (DSCs) are among the most promising cost effective and sustainable technology that could be engineered to work efficiently for indoor light harvesting. Some of these materials can even be printed onto thin, flexible surfaces or blended seamlessly into everyday objects like furniture and walls.

Image credit: https://www.niist.res.in/centre-sustainable-energy-technologies-focus-areas 

Tiny Devices, Big Potential

The beauty of indoor light harvesting lies in its simplicity and scale. Many modern electronic devices require only tiny amounts of energy, especially those in the Internet of Things (IoT). We’re talking about motion sensors, wireless tags, smart watches, digital thermometers, and even some hearing aids.

Imagine a TV remote that charges itself while sitting on the coffee table, or a sensor in a factory that never needs a battery change. These scenarios aren’t science fiction, they’re already in development or on the market.

By eliminating the need for frequent battery replacements, indoor light harvesting also reduces electronic waste, a growing global concern. It’s a small change with a big environmental impact.

How does it work?

Indoor light harvesters use special materials that are similar in concept to the ones found in outdoor solar panels to absorb light and convert it into energy. At its core, the process is simple, light hits a solar cell, which converts it into electricity that’s either stored or used to power a device. To handle the low-light environment indoors, researchers pair these solar cells with smart power management circuits that store every bit of energy in micro-batteries or supercapacitors. It’s like saving coins in a piggy bank and using them only when needed.

Is it popular?

You might wonder if indoor light harvesting is so clever/efficient, why isn’t it everywhere already? Until recently, the timing wasn’t right. Now, three key trends have changed, the rapid rise of IoT devices, the widespread use of LED lighting, and major advances in solar technology. Together, they’ve made it practical to power everyday gadgets using the light already around us. Indoor light harvesting is no longer just a good idea but it’s becoming a real solution.

Challenges to Overcome

Of course, it’s not perfect, yet! One big challenge is making sure these tiny solar cells can keep working for years. Indoor conditions are gentler than the outdoors (no rain, dust, or extreme heat), but the cells can still wear out over time. Some materials don’t handle humidity well. Others lose their performance slowly after long hours of light exposure.

Researchers are working on this by designing better, more stable materials and improving how the cells are protected or packaged. The good news is that the small size of indoor devices makes this easier than, say, building a solar farm in the desert.

Another hurdle is cost. Some of the best-performing materials are still expensive to make. But with more demand, prices are expected to drop, just like they did for regular solar panels over the past two decades.

Looking Ahead

The future of indoor light harvesting is bright, with smarter materials and real-world applications becoming a reality. Companies are testing ultra-thin solar strips embedded in smart packaging and even transparent solar films for windows. Researchers all over the world are already pushing boundaries.

In India, Council of Scientific and Industrial Research (CSIR) labs are leading this progress. Scientists at CSIR-National Institute for Interdisciplinary Science and Technology (NIIST) recently set an indoor light efficiency record of 40% using DSCs employing indigenously developed organic dyes combined with nature-friendly and earth-abundant copper-based redox electrolytes, offering a sustainable alternative to single-use batteries. In a significant step towards commercialization, NIIST has also developed the necessary scale-up fabrication equipments in-house. The team has successfully demonstrated self-powered temperature/humidity sensor prototypes operating entirely on ambient indoor light, with ongoing field trials currently underway at the Thiruvananthapuram International Airport.

Globally, researchers are developing indoor solar cells that could be built into furniture, packaging, or walls. As devices require less power, indoor light becomes a practical and sustainable energy source that powers our everyday tech without wires or waste.

Final Thought

Light is everywhere, glowing from your lamps, screens, and overhead bulbs. What used to be wasted energy is now a resource. Indoor light harvesting may not power your fridge or your car. But for the countless small devices that surround us, it offers a future where energy is always available, battery changes can become a thing of the past, and sustainability can be built into the very walls of our homes. Indoor light harvesting is a small change. But like many small changes, it could make a big difference.