PbI₂ Nanocrystal Growth by Atomic Layer Deposition from Pb(tmhd)₂ and HI

Abstract

Atomic layer deposition (ALD) allows for fine control over the thickness, stoichiometry, and structural defects of materials. ALD provides a suitable route to deposit lead halides, which can further be converted to perovskites for photovoltaics, photoemission, and photodetection, among other applications. Deposition of lead halides by ALD has already begun to be explored; however, the precursors used in published processes are highly hazardous, require expensive fabrication processes, or contain impurities that can jeopardize the optoelectronic properties of metal halide perovskites after conversion. In this work, we deposited lead iodide (PbI2) by a facile ALD process involving only two readily accessible and low-cost precursors. PbI2 nanocrystals were grown on soda-lime glass (SLG), silicon dioxide support grids, and silicon wafer substrates and provided the groundwork for further investigation into developing lead halide perovskite processes by ALD. The ALD-grown PbI2 was characterized by annular dark-field scanning transmission electron microscopy (ADF-STEM), atomic force microscopy (AFM), high resolution transmission electron microscopy (HRTEM), X-ray fluorescence (XRF), and X-ray photoemission spectroscopy (XPS), among other methods. This work presents the first step to synthesize lead halide perovskites with atomic control for applications such as interfacial layers in photovoltaics and for deposition in microcavities for lasing.

Conversion of ALD CuO Thin Films into Transparent Conductive p‐Type CuI Thin Films

“…However, the field of ALD metal halides is yet largely unexplored. In particular, for metal iodides only three processes exist so far-two for PbI 2 [47,48] and the one for CsI [49] that we developed recently.…”

Atomic layer deposition of PbCl2, PbBr2 and mixed lead halide (Cl, Br, I) PbXnY2−n thin films

“…, partial substitution of ions in the perovskite composition, for example substitution of iodine with bromine or chlorine in MAPbI 3 . 5–8,12 Currently (June 2022), to our knowledge, our iodide ALD processes, 10,11 the work of Natarajan et al on copper chloride 13 as well as the recent work of Vagott et al on PbI 2 14 constitute the entirety of existing literature on direct ALD of metal chlorides and iodides. 15 No metal bromide ALD processes have been reported.…”