Jin-Wook Lee et al. of Sungkyunkwan University, Korea, recently published a study in ACS Energy Letters (IF23.101). The metal contacts on metal halide perovskite thin films are usually formed by physical vapor deposition (PVD) processes for studying the properties of thin films or for construction of optoelectronic devices. (Note: PVD refers to a technology that uses physical processes to deposit thin films without chemical reactions. Commonly used technologies are cathode sputtering and vacuum evaporation deposition.) However, the PVD process generates high-energy metal atoms that directly bombard the film surface and may cause unexpected damage to the film. In this study, the authors systematically investigated the impact of a PVD- processed metal contacts on the optoelectronic properties of underlying organic-inorganic hybrid perovskite thin films.

　　The authors used physically laminated van der Waals metal contact for comparison for quantitative analysis. The results of the study found:

1. Through space-charge-limited current measurement, it was demonstrated that the defect density increased by an average of 26-48% after forming metal contact through the PVD process.
2. In-situ photoluminescence measurements show that the resulting defects can easily migrate under the electric field, which can seriously affect the performance and stability of photodetectors.

　　This study highlights the importance of the integrity of the intact junction between perovskite and metal contacts for the characterization and optoelectronic application of perovskite thin films.