Multifunctional KBiFe2O5 thick film: advances in functional properties

This paper presents the preparation of KBiFe2O5 thick film and its optical (bandgap), ferroelectric, and photovoltaic properties. The XRD of KBiFe2O5 film reveals orthorhombic crystal structure. The polarization study with an electric field (P–E) shows unsaturated and leaky nature of the hysteresis loop. The film shows fatigue-free polarization till 107 switching cycles. A weakly ferromagnetic behavior is observed in the KBFO film at room temperature arising from the canting of G-type antiferromagnetic spins. The film shows spin-frozen behavior below 125 K. The bandgap value of KBiFe2O5 film is found to be 1.67 eV, which is appropriate for visible light absorption. The photovoltaic study on KBiFe2O5 film gives Voc = 1.89 V, Jsc =  − 3.04 × 104 A/cm2, and photovoltaic efficiency 0.11%. The photo-ferroelectric coupling in KBiFe2O5 film is established from the directional change in photocurrent with the polarization switching under forward and reverse fields and also from the enhancement of polarization under light illumination.