Efficiency breakthrough for OLEDs

A TEAM of scientists believe they have come up with a way of making organic LEDs (OLEDs) more efficient.

OLEDs have promising applications in architecture and in slim light fittings. The study found that the tested blue OLED produced 1000 candela per square metre at 3.4 volts, which was less than 50 per cent of the voltage required by other tested blue OLEDs.

The researchers from organic photovoltaic cell development company Nextgen Nano has discovered a means of producing OLEDs that demonstrate high luminosity at lower voltages.

The findings, published today in the scientific journal Nature Communications, could lay the groundwork for efficient high-performance OLED devices in the future and may change future approaches to organic semiconductor technology.

The research, led by Nextgen Nano’s New Fusion division at a laboratory at the North Carolina State University in the United States , found that certain organic molecules were able to achieve electroluminescence at lower driving voltages than is typically required by current OLEDs.

These molecules exhibited fluorescent properties at lower energy values, allowing them to illuminate at notably lower voltages than phosphorescent OLEDs and to produce a stable blue OLED with a higher operating power efficiency compared to existing blue phosphorescent OLEDs.

This research means that it is possible for display applications in the future to provide superior levels of luminosity while using half the energy, which will also extend the operational life of the device.

The study found that the tested blue OLED produced 1000 candela per square metre at 3.4 volts, which was less than 50 per cent of the voltage required by other tested blue OLEDs.

The research was headed up by Felix N Castellano of  North Carolina State University’s (NCSU) Department of Chemistry, and Franky So of NCSU’s Department of Materials Science and Engineering.

Professor So is also chief technology officer of Nextgen Nano and has worked with OLED technology extensively in the past, having previously serving as head of Motorola’s OLED research group.

‘With this research, we’ve found a way to overcome the traditional energy limitations of OLED technology,’ Proffessor Castellano told Lux.

‘By choosing organic material with the right molecular properties, we can achieve electroluminescence at voltages below the molecule’s bandgap voltage. This results in significantly lower power consumption for devices, without sacrificing the stability or luminosity of the display.

‘If these OLEDs were used in a smartphone display, the brightness of the screen would draw less power from the battery. Not only would this extend the phone’s battery life, we expect that this lower operational power could also maximise the operational lifespan of the OLED, but we will conduct further experiments to confirm this.”

In addition to research into OLED technology, New Fusion has been actively researching the development of organic photovoltaic (PV) cells that can be used in the next generation of solar technology. This technology is being developed with NextGen Nano, with the aim to produce low-cost, high efficiency PV technology that is flexible and sustainable.

‘The current challenge in the OLED technology is blue,’ according to Professor So. ‘Our finding shows that it is possible for make a fluorescent OLED with half of the voltage required for phosphorescent OLEDs. And that can significantly improve the device operating lifetime.’

 

  • The full findings of the research can be read here .

 

  • See the latest OLED luminaires and light engines at LuxLive 2019, taking place at LuxLive 2019. The exhibition takes place on Wednesday 13 November and Thursday 14 November 2018 at ExCeL London. Entry is free if you pre-register HERE.