High-Performance Phototransistor Based on Graphene/Organic Heterostructure for In-Chip Visual Processing and Pulse Monitoring

摘要

Mimicking the real-time sensing and processing capabilities of human retinaopens up a promising pathway for achieving vision chips with high-efficientimage processing. The development of retina-inspired vision chip alsorequires hardware with high sensitivity, fast image capture, and the ability tosense under various lighting conditions. Herein, a high-performance phototransistorbased on graphene/organic heterojunction is demonstrated with asuperior responsivity (2.86 × 10~6 A W~（?1）), an outstanding respond speed (risetime/fall time is 20 μs/8.4 ms), and a remarkable detectivity (1.47 × 10~（14） Jones)at 650 nm. The phototransistor combines weak-light detection capability(minimum detectable light intensity down to 2.8 nW cm?2) with gate-tunablebi-directional photoresponse capable of simultaneously sensing and processingvisual images for light intensities ranging over six orders magnitude(10–107nW cm~（?2）). Moreover, the phototransistor also exhibits an intriguingfeature undiscovered in other retina-inspired devices, namely that it canreal-time monitor the human pulse signal and heart rate by using photoplethysmographytechnology, and the measured heart rate error is only 0.87%compared with a commercially available sensor. This study paves the way forthe development of low-light and bio-signal sensitive artificial retinas in thefuture.