French Startup Scratches the Surface with Organic Photodetectors


Isorg might sound like an Internet address, but the spinoff from France's CEA-Liten research institute is actually developing "smart surfaces" based on printed organic photonic sensors.

The company's name is short for "image sensor organic." Isorg wants to leverage its ability to produce large sensors printed in various sizes and shapes. The resulting smart surfaces are mining a wealth of applications, ranging from automated brightness controls for displays that account for ambient conditions to nontouch user interfaces that prevent the spread of bacteria in medical applications.

The startup was formed in May 2010 to commercialize the results of printed organic photonic sensor research at CEA (Commissariat à l'énergie atomique) and CEA-Liten (Laboratoire d'Innovation pour les Technologies des Energies Nouvelles). That Grenoble-based lab, employing about 1,000 researchers, focuses on renewable energy technologies and nanomaterials.

Isorg is led by CEO Jean-Yves Gomez; Laurent Jamet, business development director; and CFO Emmanuel Guerineau. Gomez and Jamet both previously worked for STMicroelectronics.

Now they are commercializing development that originated in research on organic photovoltaics. The organic photodetector is based on a photodiode device structure. The decision to focus on the technology stems from potential cost savings compared with silicon and the relative ease of recycling the material.

A typical organic photodetector material is PEDOT-PSS (polyethylenedioxythiophene mixed with polystyrene sulfonate). It is processed in solution onto low-cost plastic or glass substrates under ambient air pressure and temperature conditions rather than by using vacuum and high-temperature processes. A high external quantum efficiency, or incident-photon-to-current conversion ratio, is obtained by blending two organic semiconductors (a p-type and an n-type) sandwiched between electrodes. Excitons generated by photons are separated into electrons and holes to create an electric current. The deposition of organic materials to a thickness of only a few tens of nanometers can be achieved in a Class 10,000 clean room. The typical, small sensor size is about 1 mm2.

"The response is both in the visible spectrum and near-IR," says Jamet. "We differ from OLEDs, which need vacuum processing."

Isorg is working on different materials and processes for different applications. "Organic materials are sensitive to ultraviolet light, air and humidity, so we need a barrier to protect them," Jamet says.
What about reliability? "Today, we do not have all the answers about reliability," Gomez acknowledges. "But we have detectors made two years ago that are still alive."

Outlook for apps

There are two classes of potential applications for Isorg's printed organic sensors. The first is use of a single sensor or a few large-area sensors to capture light. "The end application could be process control for industrial, pharmaceutical or food production," Jamet says, adding that an organic sensor can replace a silicon detector.

Isorg's sensors can be applied to flexible plastic substrates, meaning a specific form factor can be offered. "We could do well where the principle is known but the solution is expensive," says Jamet.

Second, the devices could be deployed in sensor arrays that could be used for imaging, nontouch control and even gesture recognition. "There are many applications where touch control is not desirable, [such as] in medical equipment and certain industrial applications," Jamet notes.

The startup is betting there are other applications in consumer electronics, with the devices used either as a replacement for or as a complement to CMOS image sensor-based recognition, much as the PrimeSense device is used in Microsoft's Kinect game console.

"We can work close to the surface, which a camera typically cannot do. And if you compare the power consumption for gesture recognition, it would be interesting," Jamet says.

Isorg is working with some unidentified customers. The company already has a pilot manufacturing line under construction on the CEA-Liten campus in Grenoble and has plans for its own manufacturing line by 2013.

"Generally, we supply the sensor to the customer. But we know how to do microelectronics, so for some SMEs we are going to define the complete electronic application," Gomez says.

Demonstrators for the technology are key. One such vehicle is the Magic-Pad, which Jamet describes as a "smart surface" with 100 sensors. "This is a 3-D interactive interface and scanning function," he says.

For now, the company is focusing on batch rather than reel-to-reel production, Jamet says. "We use foils of 320 mm x 380 mm, but with reel-to-reel it is very difficult to get the alignment required for 100-micron pixels."

Gomez says Isorg is planning a Series A funding round this year. The size and source of the round will depend on how work progresses with early customers.

Peter Clarke