Bipolar Light-Addressable Potentiometric Sensor Based on Fullerene Photosensitive Layer

Light-addressable potentiometric sensor (LAPS) is highly attractive in many sectors, including human disease detection, drug screening, and environmental monitoring. Currently, classical LAPS chips adopt inorganic semiconductors, such as silicon, as the photosensitive layer. Organic semiconductors can provide the next generation of the photosensitive layer because of their high absorption efficiency, large structural variability, eco-friendliness, and bendability. However, no promising organic materials have been reported so far for the construction of LAPS chips. Here, the authors demonstrate the potential of fullerene (C-60), a pi-conjugated carbon molecule with high n-type conduction, as a candidate material for the photosensitive layer of LAPS. They report on a peculiar bipolar photo-response under both reverse and forward biased conditions for C-60-based LAPS. An oxygen-trap-induced space-charge mechanism is proposed to explain the unique bipolar photo-response phenomenon. The proposed C-60-based LAPS exhibits an excellent pH sensitivity of 150 mV/pH as well as a high spatial resolution of 3.8 mu m. The authors anticipate that these results will spark interest in this field and enable the replacement of the inorganic-semiconductor photosensitive layer by organic semiconductor materials for the construction of high-performance LAPS.

Automated summary

The authors demonstrate the potential of fullerene (C-60) as a candidate material for the photosensitive layer of LAPS, and propose a unique bipolar photo-response phenomenon. They explain this phenomenon with an oxygen-trap-induced space-charge mechanism.