Substrate- and layer-effects on structural and photovoltaic properties of spin-coated Aurivillius-type Bim+1Fem-3Ti3O3m+3 thin films

Driven by their ferroelectric, semiconducting, photonic, etc. properties, the potential of Aurivillius-type oxides of binary Bi4Ti3O12-BiFeO3 system in photovoltaic area is increasingly being studied. In this work, Bi5FeTi3O15 (BFTO-4), Bi(6)Fe(2)Ti(3)o(18) (BFTO-5) and Bi2Fe3Ti3O21 (BFTO-6) thin films on soda-lime glass, indium tin oxide (ITO) glass, silicon wafer and Pt/Ti/SiO2/Si substrate were prepared by the chemical solution deposition technique. The photovoltaic responses of the substrate/BFTO-4/Au devices measured by adapting top-top or top-bottom electrodes were observed. All devices present a similar linear dark J-V curve disjointed to zero point and their photovoltaic properties strongly depended on the substrates and electrode connection forms, arising from self-polarization and interface barrier potential. The optimal photovoltaic effect was observed in the BFTO-4 films on Pt/Ti/SiO2/Si substrate without any poling, with the short circuit current (J(sc)) of 18.4 mu A/cm(2) and open circuit voltage (V-oc) of 0.14 V under light illumination, which is attributed to larger polarization and c-axis oriented structure. Furthermore, layer effects on photovoltaic properties of the BFTO-4, BFTO-5 and BFTO-6 films deposited on ITO glass were also investigated. With the increase of layers, the devices exhibit an enhancement of J(sc) along with the V-oc reduction, due to the intrinsic layered structures with different lattice strains. The switching photocurrent behaviors of the BFTO-4 film by typical ON/OFF light measurements verified the stability and reliability of the photovoltaic effect. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Driven by their ferroelectric, semiconducting, photonic properties, Aurivillius-type oxides of the binary Bi4Ti3O12-BiFeO3 system have shown potential in the field of photovoltaics. The optimal photovoltaic effect was observed in BFTO-4 films on Pt/Ti/SiO2/Si substrate, while an increase in layers led to an enhanced current response along with a reduction in open circuit voltage.