Antiperovskite Sr <sub>3</sub> MN and Ba <sub>3</sub> MN (M = Sb or Bi) as promising photovoltaic absorbers for thin‐film solar cells: A first‐principles study
Youngho Kang
Abstract
Abstract Although lead halide perovskites (LHPs) have emerged as interesting photovoltaic (PV) absorbers for thin‐film solar cells, the toxicity of Pb and poor materials stability have hindered the commercialization of solar cells using LHPs. Herein, using density functional theory (DFT) calculations, we suggest antiperovskite nitrides Sr 3 MN and Ba 3 MN (M = Sb or Bi) as potential Pb‐free PV absorbers for thin‐film solar cells. State‐of‐the‐art DFT calculations based on the GW approximation show that these compounds have direct bandgaps suitable for PV applications. In addition, they exhibit significant absorption coefficients over 10 5 cm −1 for the visible light. By calculating spectroscopic limited maximum efficiency, we demonstrate that the film thicknesses of several hundred nanometers are enough for Sr 3 MN and Ba 3 MN to generate high‐power conversion efficiencies over 20%. The analysis of the electron and hole effective masses reveals that these compounds have efficient carrier‐diffusion paths allowing for the facile extraction of photocarriers. Lastly, we investigate the band alignments of the materials to help the design of thin‐film solar cells.