Optical Analysis of Ferroelectric Perovskite [MDABCO](NH4)I3
Open Access
- Author:
- Martin, Caitlyn
- Area of Honors:
- Engineering Science
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Venkatraman Gopalan, Thesis Supervisor
Gary L Gray, Thesis Honors Advisor - Keywords:
- Optical Second Harmonic Generation Polarimetry
Organic Perovskite
Ferroelectricity
Piezoelectricity - Abstract:
- Optical Second Harmonic Generation (SHG) polarimetry can provide key insight into the optical properties of polar materials. It is a process whereby the frequency of an incoming beam (called fundamental beam) is doubled by the crystal to create a second harmonic (SH) signal; this can occur only in crystals with broken inversion symmetry. Polarimetry refers to the systematic variation of the polarization of fundamental light and detecting the polarization of the SH light. Recently, a new family of organic, ferroelectric perovskites, which are polar, have been the focus of research, as they have many advantages over their inorganic perovskite counterparts including the cost of production and nontoxicity. [MDABCO](NH4)I3, where the MDABCO is N- methyl-N'-diazabicyclo[2,2,2]octonium, creates this SHG light as a result of its lack of inversion symmetry that is a key signature of polar materials.. Its piezoelectricity can be utilized for many applications, such as solar cell technology and biomedical electronic devices. The absorption spectrum was first observed for the specific crystal for wavelengths ~850-250nm, and an absorption coefficient of 54.423 mm-1 was detected at a wavelength of 800nm, which was compared to another characterization study (Ye et al., 2018). This wavelength was used for the fundamental beam in SHG polarimetry, and 8 sets of polar plots were collected for two different orientation-based parameters. From these polar plots, the relative coefficients of the SHG tensor were calculated (the d31 term was fixed to 1.00) under a set number of assumptions regarding the initial orientation angle offset and refractive indices. Further research to determine the full optical characterization, orientation, and domain analysis is proposed.