The United States has found a new method to increase the luminous efficiency of LEDs under low voltage

According to a recent report by the Physicists' Organization website, researchers at the Massachusetts Institute of Technology in the United States have used a socket conversion device to enable light-emitting diodes ( LEDs ) to release more light power than the electrical power they consume , with a power conversion efficiency of more than 100%. The relevant research was published in the latest issue of Physical Review Letters.

LEDs convert electrical energy into light. Currently, one of the biggest obstacles to designing bright and efficient LEDs is that increasing the output power of LEDs actually reduces their efficiency. MIT researchers explained that their research results significantly reduce the applied voltage. According to calculations, when the voltage is reduced to half, the input power is reduced by 4 times, while the light power emitted remains the same as the voltage, reaching half. In other words, the LED luminescence rate increases when the output power decreases.

In their experiments, the researchers reduced the input power of the LED to just 30 picowatts and measured an output of 69 picowatts of light, an efficiency of 230 percent. The same physics applies to any LED, where electrons and holes have a certain probability of producing photons under an applied voltage . Rather than trying to increase that probability, as other studies have done, the researchers used the small amount of waste heat generated by vibrations in the device's atomic lattice to generate more electricity.

This process of using waste heat to emit light allows the LED to cool slightly, operating like a thermoelectric cooler. While at room temperature, the cooling is not enough to provide practical temperatures, it could potentially be used to design lamps that don't generate heat. When used as a heat pump, the device could aid in solid-state cooling applications and even power generators.

In theory, this low-voltage strategy can generate photons with arbitrarily high efficiency at low voltages, and the researchers hope that the technique will provide a new way to test the limits of energy- efficient electromagnetic wave communications. While scientifically interesting, the approach will not immediately lead to the commercialization of ultra-efficient LEDs, as the demonstration project only produced small amounts of light with very low input power.