New Efficiency Record Achieved for White OLED Device

Photo of a horizontal rectangular device containing two white vertical panes side by side within a silver frame, with a cord coming out the back, sitting on a shiny surface, with a flower on its left.

Osram Opto-Semiconductors, Inc. has successfully demonstrated a white organic light emitting diode (OLED) with a record efficiency of 25 lumens per watt, the highest known efficiency achieved to date for a polymer-based white OLED. The 25 LPW cool-white-emitting device was produced by applying a standard external inorganic phosphor to Osram's record-breaking blue-emitting phosphorescent polymer device with a peak luminous efficacy of 14 LPW.

Although Osram's objective is to produce white light by mixing monochromatic emissions of red, green, and blue (RGB), the project team used the orange phosphor approach to provide a baseline for comparison as they continue their work fabricating and testing laboratory-based RGB OLED tiles.

Polymer-OLED Tunable Light Source Shows Promise of Scalability

Photo of four horizontal rectangular devices containing two vertical panes side by side within a silver frame.  The device in the front contains two blue panes; the device behind it contains two yellow-green panes; the device behind that contains two orange panes; and the device at the back contains two white panes.

The company has also developed the first polymer-OLED, "tunable" light source based on three separate, printable polymer inks emitting in the red, green, and blue portion of the spectrum.  Using ink-jet printing to pattern small three-color segments and the product's unique driver circuitry, users can regulate color from dark blue to white, or any color preference, offering freedom of design and innovative illumination solutions. Such printable OLED technology offers the advantage of large-size scalability without losses in key optical and electrical properties.

This built on OSRAM's earlier DOE milestone, an advanced prototype light source based on two discrete, two-inch x three-inch, white-emitting devices fabricated on glass substrates. Each tile in the module had a luminous efficacy of 8 LPW and a color-rendering index (CRI) of about 80. This year the same technology was used to demonstrate scalability to larger substrates, and a 6-inch x 10-inch, white-emitting device was delivered.