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

Abstract

Copper iodide (CuI) is a high‐performance p‐type transparent semiconductor that can be used in numerous applications, such as transistors, diodes, and solar cells. However, the lack of conformal and scalable methods to deposit CuI thin films limits its establishment in applications that involve complex‐shaped and/or large substrate areas. In this work, atomic layer deposition (ALD) is employed to enable scalable and conformal thin film deposition. A two‐step approach relying on ALD of CuO and its subsequent conversion to CuI via exposure to HI vapor at room temperature is demonstrated. The resulting CuI films are phase‐pure, uniform, and of high purity. Furthermore, CuI films on several substrates such as Si, amorphous Al2O3, n‐type TiO2, and γ‐CsPbI3 perovskite are prepared. With the resulting n‐TiO2/p‐CuI structure, the easy and straightforward fabrication of a diode structure as a proof‐of‐concept device is demonstrated. Moreover, the successful deposition of CuI on γ‐CsPbI3 proves the compatibility of the process for using CuI as the hole transport layer in perovskite solar cell applications in the nip‐configuration. It is believed that the ALD‐based approach described in this work will offer a viable alternative for depositing transparent conductive p‐type CuI thin films in applications that involve complex high aspect ratio structures and large substrate areas.

Influences of deposition conditions on atomic layer deposition films for enhanced performance in perovskite solar cells

“…By comparing the growth modes [52] , island growth, as the dominant growth mode on pEGDMA, was found, while nucleation on pHEMA was more similar to layer-by-layer growth. These results revealed that the density of reactant sites affected the nucleation behavior for ALD substrates [69] . Weiß et al compared the GPC of ALD CuO films on Si, Al 2 O 3 , and TiO 2 substrates at room temperature.…”

“…A similar phenomenon was found by Jur et al [68] . Demelius et al investigated the PE-ALD growth of ZnO on polyethylene glycol dimethacrylate (pEGDMA) and poly 2-hydroxyethyl methacrylate (pHEMA) [69] . They discovered more intense precursor diffusion in pEGDMA with fewer reactive sites.…”

Laboratory-scale X-ray absorption spectroscopy of 3d transition metals in inorganic thin films

“…CuI thin films were deposited via gas phase conversion from CuO thin films made by ALD. 37 In short, ALD CuO thin films were deposited according to Iivonen et al , 38 using bis(dimethylamino-2-propoxy) copper( ii ) (Cu(dmap) 2 ) and ozone (O 3 ) as precursors.…”

All–Inorganic Perovskite Solar Cells: Defect Regulation and Emerging Applications in Extreme Environments

“…Some inorganic ammonium salts have been demonstrated to serve as effective interfacial passivators, effectively reducing defects at the ETL/perovskite interface. [ 48 ] Cui et al. employed ammonium silicofluoride (ASF) as interfacial passivator at the TiO 2 /CsPbBr 3 interface.…”