Pressure-tuning of 2D perovskite materials for photovoltaic applications
Supervisor: Dr. Yang Song
Can extend to MSc?: Yes
Project Description (Abstract):
Organometal halide (OMH) perovskites or hybrid halide perovskites are emerging semiconductor materials with superior power conversion efficiency in photovoltaic devices such as solar cells. The OMH perovskite materials has a general formula of ABX3 where A=CH3NH3+(or MA) or CH(NH2)2+(or FA), or their fractional combination in the form of MAxFA1-x, B can be Sn or Pb and X=Cl, Br and I (see Figure 1 for the crystal structure). Application of external static pressure can effectively alter the crystal structures and produce new polymorphs with improved stabilities and photovoltaic properties. For instance, using vibrational and optical spectroscopy, electrical conductivity measurements, synchrotron microdiffraction aided with first principle calculations, our group show the external pressure can significantly alter the structures of one of the OMH perovskite materials (FAPbI3) and influencing the bandgap as well as the transport properties favorable for its performance.
In this project, we will investigate the pressure tuning of another fast-evolving class of OMH perovskite semiconductors with a formula of (A’)m(A)n−1BnX3n+1 known as 2D perovskites. Here A’ is a monovalent (m=2) or divalent (m=1) organic cation that intercalate between the anions of the 2D perovskite sheets. In the 2D OMH perovskites, the organic cations serve as insulating barriers that confine the charge carriers in two dimensions and as dielectric moderators that influences the photon-generation of electron−hole pairs. The device to generate high pressures is called diamond anvil cell (DAC) with the side view shown on the right. Samples loaded into a DAC will be examined by Raman spectroscopy, Fourier transform infrared (FTIR) micro-spectroscopy, photoluminescence spectroscopy and UV-visible absorption spectroscopy as a function of pressure using the state-of-the-art optical systems in the Song Lab. Therefore, student taking this project will obtain hand-on trainings on high-pressure techniques and will develop analytical skills by using the modern laboratory instruments.
References: J. Ratté, M. Macintosh, L. DiLoreto, J. Liu, W. Mihalyi-Koch, M. Hautzinger, I. Guzei, Z. Dong, S. Jin, and Y. Song, “Spacer Dependent and Pressure Tuned Structures and Optoelectronic Properties of 2D Hybrid Halide Perovskite”, J. Phys. Chem. Lett. 2023 14, 403-412
E-mail: yang.song@uwo.ca
Group website: https://publish.uwo.ca/~ysong56/
