Researchers overcome major roadblock to unleash efficiencies of promising tech for electronic displays, solar panel applications.

Scientists in China have unlocked the potential of a radical new type of LED technology that could potentially revolutionise a key component of today’s electronic devices, making them highly energy efficient, more luminous – and possibly cheaper.

Until now, widespread commercial adoption of the perovskite light-emitting diode (PeLED) has been hindered by one major roadblock: it tends to be unstable, leading to a short lifespan.

But this week, researchers published a study that showed how the lifespan of a PeLED could be extended to more than 20 years at a comparable brightness to commercial displays. The best PeLEDs currently last for an average of a few thousand hours.

“Our work is a new approach for designing efficient, bright and stable PeLEDs for real applications,” the team from the University of Science and Technology of China, Fudan University, and Nanjing Tech University said in a paper published in the peer-reviewed journal Nature on Wednesday.

Using an alternative method to prepare perovskite – a class of photosensitive semiconducting materials – the team’s PeLEDs reached a brightness of 1.16 million nits, far exceeding the brightest commercial display screens, which usually cap out at several thousand nits. Nits are a unit of measurement used to quantify the brightness of electronic displays.

When operating at 100 nits, which meets the standard of some commercial LED products, the team’s new PeLEDs had a theoretical lifespan of more than 185,000 hours, or around 21 years.

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PeLEDs that are both durable and efficient could be used in commercial applications to create low-cost, ultra-bright lighting and high-end display screens.

Metal halide perovskites have emerged as a promising material for creating solar cells, detectors and LEDs, owing to their physical properties and the lower cost and ease of manufacturing compared to traditional LEDs.

While work has been done to improve the efficiency of PeLEDs, typical preparation methods limit brightness and operational lifetime.

To help increase luminescence efficiency, a method to prepare perovskite crystal thin films with strong space confinement has been used to confine electrons and holes into small crystals to increase their overlap, which emits light.

Most strongly space-confined PeLEDs face “severe and challenging issues”, the researchers said, including the release of energy not in light form, ion migration which causes degradation of the perovskite, and low thermal stability.

In their paper, the team proposed overcoming these issues using weakly space-confined perovskite films, which allow for larger crystals and higher temperature resistance. They were prepared by adding the compounds hypophosphorous acid and ammonium chloride to perovskite materials before performing high-temperature annealing, or a heating and cooling process.

The peak external quantum efficiency – the number of photons that escape from the device per number of input electrons – of the new PeLEDs exceeded 22 per cent, higher than strongly space-confined PeLEDs and on par with the efficiency of commercial display products.

At a brightness of half a million nits, the external quantum efficiency remained at about 20 per cent, “representing the brightest PeLEDs ever reported”, the team said.

“Furthermore, benefiting from the suppressed ion migration and better thermal stability, the extrapolated half-lifetime of the weakly space-confined PeLEDs increased to 185,600 hours under an initial luminance of [100 nits] at room temperature,” the researchers said.

The team said a third-party laboratory measured the peak luminance at just over 1 million nits and also had similar measurements for the PeLED lifetime.