Preparation And Photoelectric Properties Of PbS Quantum Dots Sensitized Organic Photodetectors

Organic photodetectors are easy to prepare large-area flexible devices due to their advantages of light weight,low cost and high flexibility,and have high competitiveness in medicine,industry,military,communication and other fields.With the development of The Times,all walks of life have more and more requirements for near-infrared detection,so the research of near-infrared organic photodetectors has attracted the attention of many scholars.As a typical material in near-infrared band,PbS quantum dots have wide adjustable band gap,good solution processing ability and high stability in air.Based on these advantages,it is logical to combine organic photodetectors with PbS quantum dots.In this paper,PbS quantum dots are combined with organic photodetectors,and the detection range of the device is extended to the near-infrared band by regulating the device structure and the quantum dots themselves.The main work is as follows:(1)Ternary bulk heterojunction organic photodetectors based on P3HT:PbS:ITIC-Th were designed and fabricated.By adjusting the ratio of PbS quantum dots in the active layer,the device had a specific detectivity of 6.7×10~9Jones at 1350nm.However,due to the serious agglomeration phenomenon of PbS quantum dots in the active layer,not only the charge transfer efficiency is affected,but also the film forming quality of the active layer is limited,resulting in unsatisfactory device performance.In addition,PbS quantum dots have oleic acid ligand with long chain structure.The existence of the ligand also limits the carrier transmission rate.Therefore,further optimization of the device is necessary.(2)Organic photodetectors based on P3HT/PbS-EDT were optimized by removing the ITIC-Th in the active layer,designing the device as a planar heterojunction structure,and performing surface ligand exchange on PbS quantum dots.The improved device has the highest external quantum efficiency of 69.4%at 390 nm,the highest specific detectivity is 1.74×10¹² Jones,and the responsivity is 0.218 A/W,while the external quantum efficiency is 3.97%,the specific detection rate is 3.70×10¹¹Jones,and the responsivity is 0.046 A/W at 1450 nm.Compared with the bulk heterojunction structure PbS-OA quantum dots sensitized device,the performance has been greatly improved.(3)The device was further optimized,and the surface of the quantum dots film was treated with an aluminum template with nano-hole structure.Compared with the conventional P3HT/PbS-EDT detector,the performance of the device was greatly improved in the near infrared range.At 390 nm,the external quantum efficiency is 70.6%,the spectral responsivity is 0.222 A/W,and the specific detectivity is 1.92×10¹²Jones.At1450 nm,the external quantum efficiency is 24.0%,the spectral responsivity is 0.280A/W,and the specific detection rate is 2.43×10¹²Jones,and at negative bias,it is still higher than 2×10¹¹Jones at 1400nm.In addition,the device has a low response time,the response time is 35?s and the recovery time is 30?s at 650 nm,the response time is25?s and the recovery time is 30?s at 1310nm.