Study of Two-Dimensional Perovskite for Optical Anisotropy and Filter-Free Color-Selective Image Sensor

• Main Authors: Pei-Ju Tsai, 蔡沛儒
• Other Authors: Hsuen-Li Chen
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/v86rfp

碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 106 === ABSTRACT Two-dimensional (2D) perovskites are attractive materials due to their amazing optoelectronic characteristics, which are resulted from natural quantum well structures. In this thesis, the investigation toward 2D perovskites can be divided into two main parts. In first section, we focus on the intrinsic optical properties of two-dimensional perovskites. Because of the Ruddlesden-Popper phase, 2D perovskites have anisotropic properties in the direction along and across the quantum well. In addition to X-ray diffraction analysis technique, we use a simple and non-destructive method utilizing polarized ultraviolet (UV)-visible light with variable incident angles to calculate the optical anisotropy by measuring the ratio of absorption coefficients from different polarization of incident light. Subsequently, we can use the optical anisotropy to characterize the conformity of crystal orientation of 2D perovskite films. Furthermore, we also discover that the value of optical anisotropy depends on wavelength, which refers to the absorption of free carriers and excitons. In particular, we find that the generation behavior of exciton is almost optically isotropic. In the second part, the potential application of two-dimensional perovskite based photodetectors is studied. By using different 2D perovskites as light absorber, quantum confinement effect makes the produced photodetectors color selective. With the notable photoresponse located at particular wavelength, we model the performance of 2D perovskite-based photodetectors to act as a filter-free image sensor. The simulating results are shown by reconstruction of colors in ColorChecker. In addition, in appendix, we study the intrinsic silicon vacancy in silicon carbide. The intrinsic silicon vacancies of our silicon carbide samples are confirmed by measuring their photoluminescence (PL) in the wavelength of near infrared (NIR) range. The mapping PL data of silicon carbide wafer is taken to compare with the resistance data, and we speculate that silicon vacancies have some impact on electrical performance of silicon carbide.