Preparation Of Novel Quasi-2D Perovskite And Research On Polarization Detection Devices

The incoherent light with particular wavelength that emits or is reflected from the object surface usually carries information of the object itself.And the technology of polarized light detection could provide information that cannot be provided by conventional spectrum or intensity images,such as object surface characteristics,shapes,shadows,and coarseness.Therefore,the polarization detection technology is of inestimable potential in the field of optical detection.The 2D（two-dimensional）perovskite is featured in natural quantum well structure composed of inorganic framework and organic cation,showing physical property of high anisotropy.Besides,it also has outstanding photoelectric properties,which makes it possible to be applied in polarization detection.In this case,it is significantly important to explore the photoelectric response and polarization response characteristics of the 2D perovskite.（1）In this study,three types of Ruddlesden-Popper hybrid perovskites（PEA）₂Pb I₄·（MAPb I₃）_n-1（n=1,2,3）were compounded by adjusting the composition design,which were then cooled in oven to obtain crystals.And by characterizing the crystals,the structure and components were proved to meet our expectations in the design,and the grown crystals were of high quality,including comparatively low dark currents(10^-11A),and comparatively large light-to-dark current on/off ratio（10³）.（2）The photodetectors were made based on the three compounded crystals,from which,the material structure,the optical wavelength,and the incident angle were found to have the greatest effects on the photoelectric properties of the device.For 532 nm light,the crystal with n=2 components showed the best photoelectric response property,obtaining 459 n A photocurrent at 90°incident angle,74.84 d B linear response range,0.467 A·W^-1 responsivity,and 108.8%EQE.For light with 633 nm wavelength,the crystal with n=3 components showed the best photoelectric response property,obtaining8.63 n A photocurrent at 90°incident angle,55.4 d B linear response range,0.131 A·W^-1responsivity,and 30.6%EQE.（3）When we tested lights with different wavelengths irradiated on the detector,we changed the test conditions to obtain the corresponding polarization response properties.It was found that,due to the strong out-of-plane anisotropy of the material itself,the incident angle had great impact on the polarization response properties of our devices.And when our detector showed powerful absorption of lights radiated on it,the dichroic ratio obtained by devices with different components were almost the same:the largest dichroic ratio of 1.78 could all be obtained at 0°incident angle,which decreased with the increase of incident angle.And all the three devices showed no polarization response at90°incident angle.When the detector’s absorption of lights irradiated on it was weak,the material structure impacts on polarization response property of dector could not be ignored:under the condition of 0°incident angle,the dichroic ratio of device with n=2components was significantly larger than that obtained by devices with other components,reaching 1.68.And this ratio also decreased with the increase of incident angle.But when the light irradiated onto the device with 90°incident angle,devices with n=1 and n=2components could still have polarization response.The research findings of this paper provides theoretical basis for application of 2D perovskite in fields of optoelectronic devices,and polarized light detection devices,etc.