Crystal Orientation and Grain Size: Do They Determine Optoelectronic Properties of MAPbI₃ Perovskite?

Abstract

Growing large, oriented grains of perovskite often leads to efficient devices, but it is unclear if properties of the grains are responsible for the efficiency. Domains observed in SEM are commonly misidentified with crystallographic grains, but SEM images do not provide diffraction information. We study methylammoinium lead iodide (MAPbI3) films fabricated via flash infrared annealing (FIRA) and the conventional antisolvent (AS) method by measuring grain size and orientation using electron back-scattered diffraction (EBSD) and studying how these affect optoelectronic properties such as local photoluminescence (PL), charge carrier lifetimes, and mobilities. We observe a local enhancement and shift of the PL emission at different regions of the FIRA clusters, but we observe no effect of crystal orientation on the optoelectronic properties. Additionally, despite substantial differences in grain size between the two systems, we find similar optoelectronic properties. These findings show that optoelectronic quality is not necessarily related to the orientation and size of crystalline domains.

Anomalous 3D nanoscale photoconduction in hybrid perovskite semiconductors revealed by tomographic atomic force microscopy

“…I 0 is assumed to be uniform beneath the AFM probe, since the entire field of view is uniformly illuminated. In addition, according to the previous studies on quantum efficiency of individual grains of polycrystalline MAPbI 3 thin films 27 , and the orientation effect to the optoelectronic properties of MAPbI 3 45 , the terms α, η, and τ are not significantly dependent on grain size or possibly varying orientations of MAPbI 3 . Therefore, Fig.…”

Shining Light on the Photoluminescence Properties of Metal Halide Perovskites

“…These findings stand; however, they are in contradiction to the observations made by Ehrler and co‐workers who studied the photoluminescence properties of large, highly oriented MAPbI 3 crystalline domains grown by flash infrared annealing (FIRA). [ 217 ] The authors did not observe changes in PL intensity or spectral position between highly ordered domains with different crystallographic orientation.…”

“…The relationship between PL and grain size is also part of the aforementioned study of Ehrler and co‐workers in 2019. [ 217 ] Here, the photoluminescence peak position of large (tens of micrometers in size) FIRA‐grown MAPbI 3 grains is fully comparable to smaller grains (hundreds of nanometers) in a film fabricated by the antisolvent method, after the PL data was corrected for self‐absorption effects. Despite the differences in the overall size, the PL properties of MAPbI 3 did not change in their studies.…”

Hot-Casting Large-Grain Perovskite Film for Efficient Solar Cells: Film Formation and Device Performance

“…The voids in the perovskite film will seriously damage the device performance [78][79][80]. In addition, the optoelectronic performance of the perovskite film is not directly related to the size of the crystalline domains [81]. A thick perovskite layer contributes to the harvesting of sufficient light absorption across the visible light range.…”