Switchable photovoltaic properties of multiferroic KBiFe 2 O 5

Abstract We report here the preparation, ferroelectric, ferromagnetic and photovoltaic properties of polycrystalline KBiFe 2 O 5 material. The formation of polycrystalline, orthorhombic KBiFe 2 O 5 is confirmed through x-ray diffraction and HRTEM. The unsaturated ferroelectric hysteresis loop after poling indicates the leaky nature of the material that might be associated with the anion (oxygen) vacancies, not with the valence fluctuations of the Fe as confirmed by XPS. A weak ferromagnetism (remanent magnetization 0.005 emu/g) in KBiFe 2 O 5 as observed from magnetisation study is resulted from high spin state of Fe 3+ in Fe 2 O 3 tetrahedron. The optically active KBFO shows switchable photoresponse with positive and negative polarities which gives photo current (J SC ) = 20.7 μA/cm 2 and photo voltage (V OC ) = 2.04 V under visible light illumination after poling. The observed switchable photo responses are explained on the basis of dipolar flipping in KBiFe 2 O 5 due to the applied poling field.