Structure Design And Performance Study Of Photomultiplication-type Organic Photodetectors

Compared with inorganic semiconductors,organic semiconductors have the advantages of wide material sources,light weight,adjustable spectrum,large area preparation,and flexibility.Organic photodetectors are expected to become the next generation of commercial photodetector devices.In order to meet the needs of weak light detection,high-efficiency organic photodetectors need to be developed,and photomultiplication organic photodetectors show great development potential.However,the current research on the photomultiplication organic photodetector is not deep enough,the performance of the device needs to be improved,and the working mechanism needs to be further explored.This thesis takes the photomultiplication organic photodetector as the research object,starting from the material selection and device structure design,to improves the detector performance,adjusts the spectral response range,and finally prepares a series of high-performance photomultiplication organic photodetectors.The main research contents are as follows:?1?High-efficiency photomultiplication organic photodetector is prepared using TAPC:C₇₀ as the photosensitive material by hole blocking layer?HBL?accumulate holes to induce electron tunneling injection mechanism.Comparing the different HBLs of PO-T2T,3TPYMB,BCP,Bm Py Pb,and TPBi,the results show that the greater the HBL's HOMO level,the lower the LUMO level,the higher the electron mobility,the more conducive to hole blocking and electron tunneling,the better the detection performance of the device.By doping Mo O₃ in the C₇₀ layer between the HBL and the active layer,the effective electron trapping effect of Mo O₃ is utilized to further reduce the dark current of the device.Finally,the EQE of the device is optimized to be exceeds 120000%,and the D^*is 5.94×10¹² Jones.This structure has also been verified in devices with Pb Pc:C₇₀ as the photosensitive material,which not only obtains high EQE,but also extends the response spectrum to 1000 nm.?2?High-efficiency photomultiplication organic photodetector is prepared using different organic donors and C₆₀ acceptors as photosensitive materials by Mo O₃ to capture electrons to induce hole tunneling mechanism.The maximum EQE of devices based on TAPC:C₆₀photosensitive materials is>70,000%and D^*>10¹² Jones;Based on aggregation-induced luminescence?AIE?material:C₆₀ as the photosensitive material device with EQE>60,000%and D^*=3.08×10¹²Jones,and the half-life of the device reaches 700 hours under continuous irradiation at 460 nm with an intensity of 1.0 m W/cm² at-8 V bias.The device based on Pb Pc/Sub Pc:C₆₀ photosensitive material has a spectral response range of 300-1000 nm and EQE?10000%.It fully shows the effectiveness of using Mo O₃ to trap electrons and induce hole tunneling to prepare high-efficiency organic photodetectors.?3?High-efficiency narrow/wide band response gain type organic photodetector was prepared using different organic donors and C₆₀ acceptor as a photosensitive material by reducing the acceptor C₆₀ doping concentration,which causes the electron/hole imbalance transmission.It shows that the narrow and broad spectral response characteristics of the device strongly depend on the absorption properties of the selected organic donor material.When TAPC,CBP,TCTA,m-MTDATA and NPB were doped with 1 wt%C₆₀ as the photosensitive layer,a visible blind narrow-spectrum response photomultiplication organic photodetector was prepared,the minimum full width at half maximum was less than 30 nm,and the maximum EQE exceeded 1000000%.When using Sub Pc and Pb Pc as the light absorbing layer,a 300-1000 nm wide-spectrum response photomultiplication organic photodetector was prepared,with a maximum EQE?100000%.Based on the above structure,through the introduction of the filter layer method,a photomultiplication organic photodetector with spectral selectivity of green light,orange light,and red light was prepared,and the maximum EQE was also on the order of 10000%.?4?The photomultiplication organic photodetector was prepared using planer heterojunction and bulk heterojunction composed of donor and acceptor as the photosensitive material by phthalocyanine acceptor to capture electron-induced hole tunneling injection as a photomultiplication mechanism.For the prepared ITO/m-MTDATA/Pb Pc/C₆₀/Al planer heterojunction device,the experiment found that the spectral response range of the device is300-400 nm when Pb Pc is thinner?10 nm?,which is consistent with m-MTDATA absorption spectrum.The spectral response range of the device is 300-1000 nm when Pb Pc is thicker?20nm?,which is consistent with the m-MTDATA/Pb Pc absorption spectrum,and the maximum EQE?1000%,D^*<10¹¹ Jones.Then,a photomultiplication organic photodetector was fabricated using bulk heterojunction.It can be seen that the performance of the prepared ITO/m-MTDATA/TAPC:Pb Pc/C₆₀/Al binary blend heterojunction photomultiplication device is improved due to the bulk heterojunction increases the separation efficiency of the exciton,the maximum EQE?2500%,D^*=1.17×10¹¹ Jones.The performanceof the prepared ITO/m-MTDATA/TAPC:Pb Pc:C₆₀/C₆₀/Al ternary blend heterojunction photomultiplication device has been further improved,and the EQE=9744%,D^*=4.48×10¹¹ Jones.