van der Waals Metal Contacts for Characterization and Optoelectronic Application of Metal Halide Perovskite Thin Films

The metal contacts on metal halide perovskite thin films are often formed through physical vapor deposition (PVD) processes for investigation of the film properties or construction of optoelectronic devices. However, the PVD processes generate high-energy metal atoms, directly bombarding the film surface, potentially causing unintended damage in the film. In this study, we performed systematic investigation on the impact of a PVD-processed metal contact on the optoelectronic properties of underlying organic–inorganic hybrid perovskite thin films. We adopted a physically laminated van der Waals metal contact for comparison to enable quantitative analysis. Through space-charge-limited current measurement, we demonstrated the defect density increases by 26–48% on average after formation of the metal contact by the PVD process. In-situ photoluminescence measurements unraveled that the generated defects easily migrate under the electric field to seriously deteriorate the performance and stability of photodetectors. This study highlights the importance of the intact junction between the perovskite and metal contacts for characterization and optoelectronic application of perovskite thin films.