Hybrid Junction-Enabled Biomimetic Human Eye Structure for Large Dynamic Range Vision Sensor

The responsive light intensity dynamic range (DR) of the human eye far exceeds that of existing visual systems, and the development of a biomimetic retinal detecting unit is currently an important challenge in the field of machine vision. Here, a two-terminal Au-contacted VO2/WSe2 heterojunction photodetector with the same adaptive DR as retinal cells is developed. It is revealed that the VO2/WSe2 heterojunction part-mimics the cone cell for strong light detection with photoresponsivity (R) of 320 mA W−1 and the Au/WSe2 Schottky contact part-mimics the rod cell for weak light detection with an R of 217 A W−1 and noise equivalent power (NEP) as low as 248.2 fW/√Hz. The dual-mode photodetector shows a fast response speed of less than 39.28 μs. Image fusion by the cone mode and rod mode shows enhanced recognition. These results demonstrate that contact engineering enables a photodetector with the functionality of both rod and cone cells, and the resulting visual imaging system can achieve performance comparable to that of the human eye in certain operating conditions.