Polymeric light-emitting diode produces reversible voltage-dependent emission

June 1, 1997
Heterojunction light-emitting diodes (LEDs) formed of a bilayer of semiconducting polymers can produce voltage-tunable emission. Researchers at the University of Rochester (Rochester, NY) developed LEDs consisting of layers of n-type (polyquinoline; PPQ) and p-type (poly(p-phenylenevinylene); PPV) films sandwiched between aluminum and indium tin oxide (ITO) electrodes. The electroluminescence color switches reversibly with applied voltage--at low voltages, the n-type layer generates the emission

Polymeric light-emitting diode produces reversible voltage-dependent emission

Heterojunction light-emitting diodes (LEDs) formed of a bilayer of semiconducting polymers can produce voltage-tunable emission. Researchers at the University of Rochester (Rochester, NY) developed LEDs consisting of layers of n-type (polyquinoline; PPQ) and p-type (poly(p-phenylenevinylene); PPV) films sandwiched between aluminum and indium tin oxide (ITO) electrodes. The electroluminescence color switches reversibly with applied voltage--at low voltages, the n-type layer generates the emission to produce one color, while at higher voltages, both layers emit, producing a second color.

Several devices with films of varying thickness were produced, which led to generation of different colors. A 40-nm-thick PPQ/25-nm-thick PPV device emitted orange light under an 8- to 10-V forward bias--n-type layer emission--while it emitted green light under 13 to 20 V (both layers emitting). A PPQ (33 nm)/PPV(117 nm) device produced yellow output under a 20-V bias, which turned to green at higher voltages.

Sponsored Recommendations

Brain Computer Interface (BCI) electrode manufacturing

Jan. 31, 2025
Learn how an industry-leading Brain Computer Interface Electrode (BCI) manufacturer used precision laser micromachining to produce high-density neural microelectrode arrays.

Electro-Optic Sensor and System Performance Verification with Motion Systems

Jan. 31, 2025
To learn how to use motion control equipment for electro-optic sensor testing, click here to read our whitepaper!

How nanopositioning helped achieve fusion ignition

Jan. 31, 2025
In December 2022, the Lawrence Livermore National Laboratory's National Ignition Facility (NIF) achieved fusion ignition. Learn how Aerotech nanopositioning contributed to this...

Nanometer Scale Industrial Automation for Optical Device Manufacturing

Jan. 31, 2025
In optical device manufacturing, choosing automation technologies at the R&D level that are also suitable for production environments is critical to bringing new devices to market...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!