Response Of Organic Photomultiplication Photodetector Based On P3HT:PC₇₀BM

High-sensitivity photodetectors have important scientific significance and application prospects in many fields such as image sensing or communications.Up to now,there are mainly two ways to improve the response sensitivity of photodetectors:reducing the dark current density and increasing the external quantum efficiency.Photomultiplication photodetector based on organic materials have presented high external quantum efficiency and low dark current density,which is one important route to realize a high sensitivity photodetector.In view of the short carrier diffusion length and low carrier mobility in organic materials,the active layer is too thick to be conducive to carrier transport and collection,and thin active layer will lead to insufficient absorption in active layer,both can adversely affect the improvement of the detector sensitivity.In this paper,firstly optimizing the thickness of the active layer of the photodetector device,and then the PEG-coated gold nanorods are implanted into the active layer,the response performance of the device has been improved by excitation of the surface plasmon resonance.The detailed contents are as follows:?1?Optimizing the thickness and the preparation process of the active layer for organic photomultiplication photodetector.The results show that the photoelectric response of the device is the best,when the spin coating speeds of the active solution is 1400 rpm?i.e.the thickness of the active layer is 230 nm?.Specifically,the detectivity of the device is up to2.07×10¹33 Jones under-17 V bias illumination,and its external quantum efficiency is 1.1×10⁵%,the corredponding responsivity is 385 A/W.Besides,it is found that the annealing operation after getting the active layer is beneficial to form the self-assembly face-on surface for the P3HT atom,which is also conducive to improving external quantum efficiency of the device.?2?The PEG-coated gold nanorods?Au@PEG NRs?were implanted into the active layer of the organic photomultiplication photodetector to investigate its effect on the detector response performance,The results show that when doped PEG-coated gold nanorods,the external quantum efficiency?EQE?of the device in the intrinsic light absorption band of P3HT:PC₇₀BM remains the same,and the device's response spectral range is obviously broadened to the infrared wavelength range.The above results are attributed to the surface plasmon resonance exited by engineering Au@PEG NRs,meanwhile this resonance triggers the efficient emission of metal thermal electrons in the infrared band.