Structural, optical, and magnetic properties of KBiFe ₂ O ₅ synthesized by a sol‐gel method using PVP as additive

Abstract KBiFe ₂ O ₅ (KBFO) is a perovskite‐like inorganic material that has great potential as an absorber material for active layers of photovoltaic devices; however, the synthesis conditions reported until now (pressure and temperature) are inappropriate for its direct deposition on the usual substrates of solar cells. Being able to synthesize these materials directly on the substrate avoids a second stage of deposition of this material, besides improving joining properties and consequently improving energy conversion efficiency. To decrease the synthesis temperature of KBFO, the sol‐gel method was used at different times and temperatures with poly(vinylpyrrolidone) (PVP) as an accelerating agent for the kinetics of formation of the phase. Thus, the formation of the KBFO phase as powder at temperatures below 550°C and atmospheric pressure with the use of PVP as a synthesis additive is reported for the first time; however, the phase was obtained with impurities and the lower the synthesis temperature the greater the presence of impurities, but the smaller the crystallite size. Two band gaps were found for the samples: one around 2.41 and 2.07 eV and the other one around 1.76 eV. Samples synthesized at higher temperatures had a paramagnetic behavior, while samples synthesized at lower temperatures had weak ferromagnetic behavior.