Rigid and flexible large-area organic photodiodes. (Credit: Canek Fuentes-Hernandez, Georgia Tech)

The performance of flexible large-area organic photodiodes has advanced to the point that they can now offer advantages over conventional silicon photodiode technology, particularly for applications such as biomedical imaging and biometric monitoring that require detecting low levels of light across large areas.

The low-noise, solution-processed, flexible organic devices offer the ability to use arbitrarily shaped, large-area photodiodes to replace complex arrays that would be required with conventional silicon photodiodes, which can be expensive to scale up for large-area applications. The organic devices provide performance comparable to that of rigid silicon photodiodes in the visible light spectrum — except in response time.

One application for the new devices is in pulse oximeters now placed on fingers to measure heart rate and blood oxygen levels. Organic photodiodes may allow multiple devices to be placed on the body and operate with 10 times less light than conventional devices. This could enable wearable health monitors to produce improved physiological information and continuous monitoring without frequent battery changes.

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