Recently the solar energy, an inevitable part of green energy source, has become a mandatory topics in frontier research areas. In this respect, non-centrosymmetric ferroelectric perovskites with open circuit voltage (VOC) higher than the bandgap, gain tremendous importance as next generation photovoltaic materials. Here a non-toxic co-doped Ba1−x(Bi0.5Li0.5)xTiO3 ferroelectric system is designed where the dopants influence the band topology in order to enhance the photovoltaic effect. In particular, at the optimal doping concentration (xopt ~ 0.125) the sample reveals a remarkably high photogenerated field EOC = 320 V/cm (VOC = 16 V), highest ever reported in any bulk polycrystalline non-centrosymmetric systems. The band structure, examined through DFT calculations, suggests that the shift current mechanism is key to explain the large enhancement in photovoltaic effect in this family.

Ferroelectrics are considered next generation photovoltaic (PV) materials. In this work, a switchable and large PV effect is demonstrated in a Pb-free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT) thin film fabricated by a pulsed laser deposition technique. The material shows a remarkable PV output of 0.81 V due to its morphotropic phase boundary composition. The observed PV effect is analyzed on the basis of the interfacial Schottky barrier and bulk depolarization field. The poling dependent PV studies revealed that although the Schottky and depolarization field contribute to the PV effect, the latter dominates the PV response beyond the coercive field. Additionally, the importance of this compound in the field of a self-biased photodetector is elucidated in terms of calculated photodetector parameters such as responsivity and detectivity. The explored results will bring significant advancement in the field of ferroelectric PV, UV solid state detector applications and also give an additional dimension to the multifunctional ability of the BZT-BCT system.

A polycrystalline BiFeO3 film on Pt/Ti/SiO2/Si was fabricated using the spin coating technique. The film shows diode-like characteristics with and without poling measured under dark conditions. However, it exhibits a switchable photovoltaic effect with light illumination under poled conditions. The measured photovoltaic effect revealed an open circuit voltage of ∼0.47 V and a short circuit current of 3.82 μA/cm2 under the illumination of 165 mW/cm2 irradiance. The studies clarified the dominant role of the depolarization field rather than the interface in the photovoltaic characteristics of the BiFeO3 film. Significantly, the photo-capacitance effect was demonstrated with a substantial enhancement in capacitance (∼45%) in Au/BiFeO3/Pt geometry, which could open up a new window for BiFeO3 applications.

BiFeO 3 is a promising multifunctional material in terms of its intriguing physics and diverse application potential. In this work, self-powered UV-visible photodetector characteristics of the polycrystalline BiFeO 3 thin film exhibiting pronounced photo-response under both UV and visible light are demonstrated. Interestingly, the film displays switchable photodetector characteristics in accordance with the polarization switching properties and thereby confirms the role of polarization driven depolarization field on the observed properties. Importantly, the photodetector performance parameters such as responsivity 23.9 × 10 −4 AW −1 , detectivity (2.2 × 10 10 Jones), photoconductive gain (8.5 × 10 −3 ), and external quantum efficiency (5.3 %) observed under UV light are 2 to 4 order of magnitude higher than the values reported in similar oxide ferroelectric systems. These studies establish the application of polycrystalline BiFeO 3 film as a self-powered UV-visible photodetector.

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