Structure-Controlled Perovskite Thin Layer Formation on Au Single-Crystal Substrate via Self-Assembled Monolayer of 4-Aminothiophenol

Abstract

1. IntroductionIn order to solve recent energy and environmental problems, construction of a photoelectric conversion device using a perovskite structure has recently attracted much attention because perovskite structure absorbs visible light very much [1]. In this type of photoelectric conversion device, it is necessary to construct on a solid substrate while maintaining the perovskite structure. In order to improve efficiency, moreover, it is important to control the interfacial structure between the solid substrate and the perovskite film by an atomic dimension. In the present study, we tried to construct a perovskite layer on a Au(100) single-crystal substrate while maintaining the perovskite structure completely and control the interfacial structure between the substrate and the perovskite layer by using a self-assembled monolayer (SAM) of 4-aminothiophenol (4-ATP) by an atomic level.2. ExperimentalAu(100) single-crystal as a substrate and 4-ATP having an amino terminal group as a SAM molecule were chosen. After annealed and quenched the Au(100) substrate, it was immersed in the hexane solution containing 1 mM 4-ATP for 3 hours at room temperature (RT). Then, the 4-ATP SAM modified Au(100) substrate was sequentially immersed in each DMF solution containing 1 mM PbBr2 and 1 mM MABr for 24 hours for 3 cycles, followed by heating at 135 °C, and then MAPbBr3 perovskite thin films were constructed on 4-ATP SAM modified Au(100) surface [2]. The structure and composition of 4-ATP SAM modified Au(100) substrate after immersion in each solution were evaluated by X-ray photoelectron spectroscopy (XPS) and the crystal structure of the constructed perovskite thin film was evaluated by surface x-ray diffraction (SXRD) as compared with XRD of the corresponding perovskite crystal.3. Results & Discussion Figure 1 shows the SXRD profile of the perovskite thin film and the XRD profile of the perovskite crystal. In the SXRD profile, only the (0kl) reflections such as (002) and (012) of the perovskite crystal, which was indicated by triangles in Fig. 1(a), and no diffraction peaks of the (hkl) (h is not zero) reflections such as (112) and (122), which was indicated by stars in Fig. 1(b), were observed. Based on these results, it is indicated that the constructed perovskite thin film was grown along the [100] direction, and we can conclude that it is succeeded to construct the structure-controlled perovskite thin film on the Au(100) surface.