Effects of Thickness and Polarization Field on the Photovoltaic Properties of BiFeO ₃ Thin Films

Abstract

We study the effects of film thickness on lattice parameters, direct band gap and photovoltaic outputs in the sol-gel derived BiFeO3 thin films. With the change of the film thickness, the great transitions will take place in the preferred orientation and lattice parameters. Furthermore, the photovoltaic outputs are significantly dependent on the film thickness. The results show that the open circuit voltage gradually increases and the short circuit current reciprocally decreases with the increase of film thickness. In particular, we demonstrate for the first time that there are tunable photovoltaic outputs with external electric field polarization switching in the polycrystalline BiFeO3 film, which is critical for the future device applications based on the photovoltaic properties of BiFeO3 films.

Correlation of film thickness to optical band gap of Sol-gel derived Ba0.9Gd0.1TiO3 thin films for optoelectronic applications

“…The decrement in band gap can be linked to the increment of grain size as discussed in AFM results, which is attributed to the quantum size effect, whereby the smaller the crystal size, the larger the energy band gap [22]. Similar reduction in optical band gap as the thickness increased has been reported by Zhou et al [23] for BFO thin films.…”

Enhanced Adjustable Photovoltaic Response in Multilayer BiFeO3 Films

“…In recent years, with the development of solar cell research, BFO was widespread concerned again for its narrow band gap (2.7 eV) in the visible light range. The narrow band gap provides potential possibilities for applications in solar cells and memory devices. − More and more researchers have observed the photovoltaic effect of BFO single crystals, films, and ceramics under visible light illumination. − Yang et al found that BFO films prepared by metal–organic chemical vapor deposition (MOCVD) can obtain a very large photovoltage . Ji et al reported the bulk photovoltaic effect of epitaxially grown BFO under visible light.…”

Improved photovoltaic effects in Mn-doped BiFeO 3 ferroelectric thin films through band gap engineering

“…[11] The BFO with a relatively low bandgap of 2.67 eV has aroused great interest in the ferroelectric photovoltaic field. [12][13][14] However photons with wavelength larger than 464 nm (accounting for more than 80% of the solar spectrum) cannot be absorbed by BFO materials either. [1,2,15,16] Recently, some novel ferroelectric materials with narrow band gap such as KBiFe 2 O 5 (1.6 eV) [17] and [KNbO 3 ] 1−x [BaNi 0.5 Nb 0.5 O 3 ] x (1.1 eV) [18] have been observed, which can effectively absorb visible light.…”