Ultra-microtome effects on lead halide perovskite defects*

Metal halide perovskites (MHPs) have demonstrated impressive properties for optoelectronics such as solar cells, photodetectors, and light-emitting diodes, with surprising defect tolerance. However, the impact from defect type on material properties and device performance is not well understood, nor is it understood how synthetic technique, device fabrication, and microstructure influence this defect landscape. Recent combined theory and experimental work has shown that n-type Bi³⁺ doping is a deep-level trap with its effects on defect states still outstanding. TEM has the potential to answer said questions if these materials can be prepared and imaged without causing additional damage. To investigate the effects caused by two competing sample preparation methods, electron transparent CsPbBr₃ specimens are fabricated with non-aqueous wet- and dry-cut ultramicrotome. EDS, diffraction, STEM, and HRTEM are used to experimentally investigate intrinsic and preparation induced defects from ultra-microtome prepared specimens and compared to similar FIB prepared specimens.