• Universitat de València

A spin valve is a device with two or more conducting magnetic materials, whose electrical resistance varies between two values depending on the relative alignment of the magnetisation in the two layers. The resistance change is the result of the Giant Magnetoresistance effect. There are currently no commercially available electroluminescent devices that exhibit spin valve behaviour. Research in this field has resulted in a number of devices capable of emitting light only at very high threshold voltages, and these devices are generally based on conventional OLED structures. For years, the main goal in this field has been to increase the spintronic polarisation of these devices.

Researchers at the Universitat de València have developed a new opto-spintronic device with low emission threshold voltage (from 2 V) in coexistence with magnetoresistance properties. These properties allow the control of the emitted light by means of magnetic fields.

The new devices design employs a Hybrid Organic-Inorganic Light Emitting Diode configuration instead of the conventional OLED configuration. The new configuration is based on the use of metal oxides as the electron injector layer, and is inverted with respect to the OLED configuration, thus making it possible to develop simpler, more efficient, air-stable and cheaper devices.

All these advantages of the HyLED configuration over OLED have had a surprising effect when applied to a new field such as spintronics. In this way, researchers have succeeded for the first time in producing an electroluminescent device controlled by magnetic fields, with low emission thresholds and high stability, and therefore of greater interest for technological applications.

Opto-spintronic devices have numerous applications in molecular electronics and molecular spintronics. The ability to control light and colour emission by means of magnetic fields is of particular interest in optoelectronic applications such as lighting, displays, etc.

The main advantages provided by the invention are:

• Efficiency: threshold voltage of light emission from 2 V.
• Stability: use of air-stable electrodes, with high working function.
• Spin valve properties (magnetoresistance): control of electrical properties by magnetic fields, e.g. light intensity or colour.
• Low cost: manufacture with commercial materials, and using solution deposition methods, which are cheaper and more viable on a large scale than evaporative deposition methods.

• Patent granted