Performance Of Perovskite Photodetectors Regulated By Surface Plasmon

Photodetectors are devices that detect and measure the wavelength and intensity of different irradiated light through the photoelectric effect,widely used in various fields of military and national economy.Organic halide perovskites show great prospects in large-area,low-cost perovskite photodetectors（PPDs）due to their simple solution preparation process,high carrier mobility,and adjustable optical absorption broadband.However,their application is limited by the high defect state density and poor stability of perovskite materials.Therefore,studying and solving the performance control problems of PPDs and improving their responsiveness and stability are the key and research hotspots in this field.This work focuses on the performance control of PPDs.We mainly study the device preparation process and control methods based on doping and local surface plasmon resonance（LSPR）.The main work and innovations are as follows:（1）The MAPb I₃based perovskite device is fabricated on a flexible polyacetimide film（PI）by a one-step spin coating method.FA cations are doped to obtain flexible lateral PPDs with the composition MA_xFA_1-xPb I₃.Through different cation ratios（MA/FA）,the morphology and crystallinity of the perovskite film can be adjusted and the light response capability of the device can be improved.The experiment finds that the best component MA_0.4FA_0.6Pb I₃device has a responsivity of 0.0111 A W^-1,a specific detectivity of 3.26×10¹⁰Jones,and a response time of t_on/t_off=89 ms/47 ms.（2）Vertical PPDs with flexible semitransparent self-powered characteristics are prepared on the MA_0.4FA_0.6Pb I₃perovskite film using ITO/PET conductive substrate.Ag NPs doping produces a strong local field of LSPR,regulates the efficiency of carrier generation,and improves the response capability of the device.F68 doping improves the humidity stability of the film.On the prepared PPDs,the optimal amount of Ag NPs（0.04 wt%）and an appropriate amount of F68 are incorporated.Under self-poweredness,the responsivity can reach 0.145 A W^-1,the specific detectivity is 9.73×10¹⁰Jones,and the response time is t_on/t_off=100 ms/153 ms.The responsiveness can still reach 80%when PPDs are placed in a high humidity environment for 7 days.The doping of Ag NPs in this process is different from the doping of FA cations in the crystal lattice.This vertical device structure and its performance control effect have greater advantages in meeting high response under low energy consumption.（3）With wavelength selective transmission effect of the LSPR metasurfaces,the narrow-band PPDs are presented based on the narrow-band blocking effect of metasurfaces,and adjustable narrow-band PPDs are developed on the MA_0.4FA_0.6Pb I₃films doped with the optimal amount of Ag NPs and F68.A series of novel structures of metal micro-nano metasurfaces are designed to achieve broadband/narrowband/multiband band-stop filtering.The electromagnetic interaction mechanism that produces this wavelength control effect is analyzed,silver disc arrays are processed and their absorption/reflection/transmission spectra are given.The results show that the LSPR resonance characteristics are consistent with the theory.Lateral PPDs based on Si O₂/silver island film/PMMA/perovskite are prepared.The obtained narrow-band PPDs have a center wavelength of 470 nm and a full width at half maximum of 145nm.