Large-Area, Flexible Near-Infrared LEDs

Using low-cost solution-processing techniques, a study team has created high-efficiency, near-infrared LEDs covering 900 mm2. Researchers point out that infrared LEDs are frequently used in remote controls and security video systems and have been used in optical communications and covert illumination. According to the researchers, they are typically small point sources, which restricts their use if closer larger-area illumination is necessary, such as on a wearable device.

It results in sizes that are many orders of magnitude larger than those made in previous efforts, and it offers up a variety of intriguing new applications. They use a new direct-bandgap perovskite-based semiconductor in their devices, capable of strong light emission.

The study team can exactly tune the injection of electrons and holes (negative and positive charges) into the perovskite by employing a new device architecture, allowing a balanced number of opposite charges to collide and result in an effective light generation. The team also discovered that this enhancement greatly increased the reproducibility of large-area devices.

Researchers discovered that hole-injection efficiency is a key element influencing how well the devices work. They have shown that the near-infrared LEDs may suit subcutaneous deep-tissue illumination uses, such as in wearable health-tracking gadgets.

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