The Preparation Of Flexible Heterojunction Based On GaSe/MoS₂ And The Study Of Its Photoelectric Properties

With the outstanding performance in the field of health care monitoring and energy collection,flexible electronic technology has attracted extensive attention.Because of its soft characteristics,it can be used on the skin surface to realize the wearability of electronic devices,and provide a lot of new functions for some applications.The use of flexible photoelectric sensors is a major trend in the field of wearable devices.Among them,the photodetector based on GaSe/MoS₂ heterojunction can achieve high-performance detection from visible light to near-infrared light with the aid of its excellent photoelectric properties and heterojunction.However,the existing photodetectors based on GaSe/MoS₂ heterostructure are almost based on rigid substrate,which can not meet the development trend of flexible wearable devices and greatly reduce their application range.Therefore,we propose a GaSe/MoS₂ heterojunction photodetector based on flexible substrate.In addition,in order to further improve its photoelectric performance,we explore the effect of external strain on the flexible photoelectric device,which provides a new way to improve the performance of photoelectric detector.The main contents are as follows.In this paper,two-dimensional material photodetectors based on ITO conductive glass and flexible ITO-PI films are studied.The GaSe/MoS₂ heterojunction is prepared by mechanical stripping and dry transfer.The photoelectric properties of GaSe/MoS₂heterojunction on rigid and flexible substrates are studied.The morphology and structure of GaSe/MoS₂ heterojunction are characterized by optical microscopy,AFM,Raman spectrometer and other devices.The results show that the heterojunction shows good rectifying characteristics for the photodetectors based on ITO conducting glass.For450nm,520nm,635nm and 808nm laser,the device shows different responsivity.At520nm,the photoelectric response of the device is stronger,the responsivity is 169 m A/W,and the D*is 5.8×10¹⁰ cm Hz^1/2/W.The rising and falling time of the device based on ITO conductive glass are about 400?s and 600?s respectively.For the GaSe/MoS₂photodetector based on ITO-PI film,the visible light and near infrared light can be detected successfully,and the photocurrent will be linearly enhanced with the increase of optical power.For the incident light at 450 nm,the heterojunction photodetector has a responsivity of 111 m A/W and the D*is 5.8×10¹⁰ cm Hz^1/2/W.The response rise time and falling time are about 50 ms and 45 ms respectively.In addition,this paper also studied the influence of different strain on the photoelectric properties of flexible GaSe/MoS₂ heterostructures.It is found that under tensile strain,with the increase of strain,the photocurrent of GaSe/MoS₂ heterojunction will increase.On the contrary,under compression strain,with the increase of strain,the photocurrent will decrease.Under the condition of tensile strain of 0.4,the responsivity and D*of the device are nearly 100%higher than those in plane.At the same time,the response time will change with the strain.The tensile strain can shorten the response time,and the greater the strain degree,the shorter the response time.The compression strain will make the response time longer,and the greater the strain degree,the longer the response time.This is due to the change of barrier height and depletion zone width in heterostructures when Ga Se and Mo S₂ are affected by strain.The width of depletion region affects the separation and transmission of photocarriers,and thus affects the performance of photodetectors.Specifically,when subjected to tensile strain,the energy band near Ga Se side of GaSe/MoS₂ interface bends upward,and the energy band near Mo S₂ side bends downward,which enhances the built-in electric field of heterojunction,widens the width of depletion zone,makes the separation efficiency of electron hole pairs higher,and improves the optical response performance.When the compression strain is applied,the energy band near the Ga Se side of the GaSe/MoS₂ interface bends downward,and the energy band near Mo S₂ side bends upward,which reduces the separation efficiency of the electron hole pairs and weakens the optical response performance of the device.The results of this study provide a new way to improve the response of photodetectors.