Band Offset Engineering in ZnSnN₂‑Based Heterojunction for Low-Cost Solar Cells

A new ternary-alloy, zinc–tin nitride (ZnSnN₂), is considered as one of the most promising absorber materials for photovoltaic applications due to its ideal band gap, rich ternary-chemistry, robust optical absorption, and low cost. In the present work, we demonstrate the ZnSnN₂-based P–N and P–i–N heterojunctions to study the band offset engineering for the development of high-efficiency inorganic solar cell. The P–i–N heterojunction is composed of <i>p</i>-SnO, <i>i</i>-Al₂O₃, and <i>n</i>-ZnSnN₂ constituents. The inclusion of the <i>i</i>-Al₂O₃ buffer layer has remarkably improved the solar cell efficiency by regulating the conduction band offset and interface energy gap. It is believed that our present work will offer a promising approach to manufacture ZnSnN₂-based heterojunctions with better band alignment for novel photovoltaic applications