Cai T.-Y.Liu S.-C.Ju S.Liu C.-Y.Guo G.-Y.2019-05-102019-05-10201723317019https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030090772&doi=10.1103%2fPhysRevApplied.8.034034&partnerID=40&md5=ab9291baf33ba31196c95e52127c0f4ahttps://scholars.lib.ntu.edu.tw/handle/123456789/407250Ferroelectric oxides are attractive materials for constructing efficient solar cells. Nevertheless, a wide band gap of nearly 3.0 eV in these ferroelectric oxides would result in poor overall sunlight absorption and, hence, low energy conversion efficiency. Here, by systematic first-principles density-functional calculations, we demonstrate that double-perovskite semiconductors ScFe1-xCrxO3 (1/6≤x≤5/6) with a narrow band gap of approximately 1.8 eV would simultaneously exhibit large ferroelectric polarization (100 μC/cm2) and ferrimagnetic magnetization (170 emu/cm3). Within a Schottky-based model for a typical sandwich solar-cell structure, a power-conversion efficiency of 9.0% can be reached by neglecting all other sources of photovoltaicity in ferroelectric materials. This value is larger than the largest value of 8.1% observed in ferroelectric oxides. Furthermore, these double perovskites are found to be single-spin semiconductors, and the obtained photocurrent is fully spin polarized over almost the entire Sun spectrum. These fascinating advantages would make ScFexCr1-xO3 (1/6≤x≤5/6) semiconductors promising candidates for highly efficient solar cells and spin photovoltaic devices. © 2017 American Physical Society.[SDGs]SDG7Calculations; Conversion efficiency; Energy gap; Ferroelectricity; Narrow band gap semiconductors; Perovskite; Solar cells; Solar power generation; Ternary alloys; Thallium alloys; Wide band gap semiconductors; Double perovskites; Ferroelectric oxides; Ferroelectric polarization; First-principles density functional calculations; Fully spin-polarized; Power conversion efficiencies; Solar cell structures; Spin photovoltaic; Ferroelectric materialsjournal article10.1103/PhysRevApplied.8.0340342-s2.0-85030090772