Research On Self-powered Broadband Opto-sensor Based On Two-dimensional γ-InSe And Its Human Eye Bionic Function

Vision is an important perceptual function in humans and other vertebrates,contributing more than 80% of perceptual information to the brain.With the rapid development of artificial intelligence,artificial vision systems are required to be able to mimic the visual perception ability of human eyes,and one of the important functions is visual adaptation,which can automatically adjust the response to stimuli according to different light environments.However,artificial vision systems that can imitate visual adaptation at this stage usually require complex hardware and algorithms to cooperate,which seriously limits operational efficiency.In order to improve efficiency and reduce complexity,research on artificial vision systems based on a single device configuration with integrated visual adaptation has been carried out to replace traditional solutions that require complex circuits and algorithms.However,their working mechanism is mainly limited to the regulation of carrier capture or ion migration,which does not meet the development needs of future visual adaptive devices for artificial vision systems.Based on this,this paper develops a two-terminal opto-sensor based on multilayer γ-InSe sheet,and the new working mechanism combining photo-pyroelectric and photo-thermoelectric effect enables the device current to dynamically adapt to constant light stimulation,emulating the visual adaptation behavior well.In addition,thanks to the relatively small bandgap of γ-InSe and the photovoltaic effect,the device can operate in self-powered mode and exhibit good human eye adaptation behavior,including: strong background scintillation signal recognition,near-one photosensitive recovery,collaborative visual adaptation function of retina and eyelid,and wideband photosensitive image adaptation.The specific research content and main conclusions are as follows:1.Design and build a visual adaptive bionic light sensor based on 2D γ-InSe.With the goal of building devices with adaptive light response characteristics,the construction ideas of "non-central symmetry" and "asymmetric contact" are designed.First,the non-central symmetric γ-InSe was selected to obtain considerable pyroelectric instantaneous response spikes by taking advantage of its non-center-symmetric crystal structure and excellent photoelectric properties.High-resolution transmission electron microscopy,selective electron diffraction,X-ray diffraction,and Raman spectroscopy characterized the mechanically exfoliated sample as an non-central symmetric γ phase.By measuring the second harmonic signal generated by the material to the excitation light at 1064 nm,it was again verified that it had non-central symmetric structural characteristics.Then,parallel asymmetric contact(area)electrodes are built on the surface of γ-InSe to obtain a thermoelectric current that gradually decreases as the thermal equilibrium is established,and the spontaneous relaxation of the current after the spike is realized.2.The analysis elucidates the working mechanism of 2D γ-InSe-based adaptive light sensors.The influence of carrier capture at the interface of the material on the adaptation behavior of the device was ruled out by comparative experiments.Aiming at the dynamic light response process of the device under continuous illumination,the mechanism conjecture of photo-thermal-electric conversion dominated by photo-pyroelectric effect,photo-thermoelectric effect and photovoltaic effect is proposed.By testing the Raman spectrum and the optical response of the device with variable temperature,variable bias voltage and variable laser irradiation area,the adaptive response behavior with temperature and spot heating area was obtained,and the contribution of photo-pyroelectric effect and photo-thermoelectric effect to the adaptive behavior of the device was confirmed.By testing the volt-ampere characteristic curves of the device under dark state and incident light of different power density,the open-circuit voltage and short-circuit current of the device are obtained,which confirms the contribution of photovoltaic effect to the self-driving adaptive behavior of the device.3.Realize the simulation of adaptive bionic function of human vision.Aiming at the adaptive response characteristics of the device with light intensity and wavelength changes,a variety of adaptive scenarios for the human eye are designed and simulated.In terms of the function of analog recognition of strong background flashing signals,a "flashing sign" scenario is created,and the device can quickly complete the recognition of the "light" information within 10 flashes.In terms of simulated photosensitivity recovery,the sensitivity recovery function of the human eye experiencing a dark interval between two identical light stimuli was simulated,and the sensitivity recovery of the device at the 60 s dark interval could reach 99.6%.In terms of simulating the visual adaptation function of human eyelid coordination,the device can simulate the adaptation time required in different eye opening situations,compared with the 70 s relaxation time to equilibrium required for direct eye opening adaptation,and the device only takes 40 s to complete in the slow opening situation.In terms of analog wide-band optical perception image adaptation,the image perception ability of red,green and blue band devices was tested,and the simulation results showed that the device can accurately and clearly identify color signals in about 2 s.