Solvent and A‑Site Cation Control Preferred Crystallographic Orientation in Bromine-Based Perovskite Thin Films
Juanita Hidalgo, Yu An, Dariia Yehorova, Ruipeng Li, Joachim Breternitz, Carlo A.R. Perini, Armin Hoell, Pablo P. Boix, Susan Schorr, Joshua S. Kretchmer, and Juan-Pablo Correa-Baena
Chemistry of Materials 2023 35 (11), 4181-4191
DOI: 10.1021/acs.chemmater.3c00075
This scientific article investigates the factors that determine crystallographic orientation in lead bromide perovskites. The researchers show that the solvent and organic A-site cation play a critical role in preferred orientation of the thin films. The results reveal that the solvent, specifically dimethylsulfoxide (DMSO), influences the early stages of crystallization and induces preferred orientation by preventing colloidal particle interactions. Additionally, the choice of A-site cation, such as methylammonium or formamidinium, affects the degree of preferred orientation. Density functional theory calculations suggest that the difference in surface energy between the (100) and (110) facets is the reason for the varying degrees of preferred orientation. Besides, the researchers observe that the choice of A-site cation impacts ion density and accumulation, leading to increased hysteresis in solar cells. Overall, this study highlights the importance of solvent and A-site cation in determining crystallographic orientation and its impact on the electronic and ionic properties of solar cells.
How Litos Lite & Paios were used
LITOS LITE was used to measure the current density-voltage (J-V) characteristics of the solar cells. The J-V curves were obtained by scanning voltage in the range from 1.4 to -0.5 V with a scan speed of 50 mV·s-1 first in reverse and then in forward scan directions. The active area of the device was 0.128 cm2, and a black metal mask with an aperture area of 0.0625 cm2 was used to define the illuminated area.
Impedance Spectroscopy: #PAIOS was used to perform Impedance Spectroscopy (IS) on complete solar cells at room temperature under one sun illumination and in ambient air. The measurements were performed at five different offset voltages spaced from 0 V to the open circuit.