Discovering Low-Electron-Affinity Semiconductors for Junction Partners of Photovoltaic BaSi2 by Database Screening and First Principles Calculations

Finding an appropriate heterojunction partner is important for developing high-efficiency solar cells using emerging materials. n-Type BaSi2, which has proven to possess excellent optoelectronic properties, lacks an appropriate junction partner. This study finds out junction partner candidates from the Materials Project database, considering both the band alignment and interface reactivity, based on a previous device simulation study. From binary and ternary compounds including Ba or Si, 19 compounds pass the screening steps including band gap, phase stability, and interface reactivity. Considering air sensitivity and reported ionization potential, the candidate list is narrowed down to 11 compounds. Density functional theory calculations reveal that all of them have an unusually low electron affinity of