A digital database of photoelectron yield spectroscopy (PYS) was constructed to provide information on ionization potentials of organic and inorganic semiconductor materials. The keys (metadata) for the search were organized as follows. (1) measurement metadata obtained from measurement instruments, (2) data analysis metadata, (3) sample and experiment metadata describing measurement samples and experimental procedures, and (4) metadata about data licenses. For low-molecular-weight organic materials, metadata such as SMILES converted from matrix notation structure files to linear notation was included in order to uniquely identify the material name. This enables linkage with external databases on organic materials.