| The organic photodetector(OPD)has the advantages of low cost,high efficiency,wide material source and simple preparation process,and has begun to show bright prospects.However,it is currently limited by the lower carrier mobility of the organic polymer in the active layer(about 2×10-3 cm2/Vs),the shorter exciton diffusion length(?10 nm),and the narrower spectral response and the morphology of the interpenetrating network required for charge transport is not optimized enough.This paper adds new component one-dimensional nanostructures such as single-walled carbon nanotubes(SWCNTs)to broaden the spectral response or serve as an effective exciton dissociation center and charge conduction pathway.Thereby achieving a good response of the broad spectrum at visible light region.In the research process,a three-primary color spectral response detector was fabricated using the structure of bulk heterojunction.The structure is:ITO/PEDOT:PSS(30 nm)/PBDTTT-F:P3HT:PC61BM:SWCNT/LiF(1 nm)/AL(100 nm).In order to further explore the effect of SWCNT on the formation of active layer,the optical and electrical properties of the device with single-phase PBDTTT-F:SWCNT were investigated.The results show that with the incorporation of SWCNTs,the optical responsivity increases and the fluorescence spectrum is quenched.When the bias voltage is-1 V,when the SWCNT doping ratio is 0 wt%,1 wt%,2 wt%,3 wt%,4 wt%,the photocurrents are 0.192,0.302,0.368,0.476,0.411 mA/cm2,respectively,showing a tendency to gradually increase and then decrease,reaching a maximum at a blending ratio of 3 wt%.The optical and electrical properties of the device with the active layer as two-phase PBDTTT-F:PC61BM:SWCNT were then investigated.Based on the above system,the PC6,BM acceptor polymer was added to form a device structure with a balanced system,and the blend ratio of PBDTTT-F:PC6:BM was 1:1.5.The optical properties also show a red shift of the absorption spectrum and a tendency to increase,indicating that the crystallinity of the film is enhanced and the absorbance is enhanced.The electrical characteristics are as follows:when the applied bias voltage is-1 V,the doping ratio is 1.5 wt%,it is an optimized device,which is 388,436 mA/W under blue light and red light,respectively,which is nearly 2 times that of similar photodetectors.The average external quantum efficiency EQE of the device is more than 50%as a whole,and reaches 104%when the incorporation ratio is 1.5 wt%,exhibiting a photomultiplier effect.Finally,the paper systematically studied the effects of SWCNTs on the absorption spectrum,optical responsivity,quantum efficiency and specific detection rate of the organic three-phase heterojunction active layer detector by using experimental methods and its mechanism.On this basis,the average optical responsivity of the blue,green and red primary colors of the detector is 475 mA/W at a bias voltage of-1 V,which is 2-3 higher than that of the similar devices.The average external quantum efficiency EQE reached 111%;the specific detection rate reached 6.5 × 1011 Jones.The results show that the incorporation of single-walled carbon nanotubes in the three-phase bulk heterojunction active layer can maintain the original spectral morphology,increase the aggregation and crystallinity of the organic conjugated polymer,enhance the light absorption,and the number of mixed phases with the film.How much the phases is irrelevant;can increase the exciton dissociation area,increase the dissociation rate of the film,and provide a fast transport channel for the charge,improve the charge collection of the electrode;single-walled carbon nanotubes produce a photomultiplier effect in the range of 0.75-1.75 wt%and high photon energy excitation. |
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