Photovoltaic effect in a wide-area semiconductor-ferroelectric device

Abstract

Millimeter-diameter planar devices of glass/ZnO:Al/BiFeO3/La0.67Sr0.33CoO3 (LSCO) heterostructures were fabricated by pulsed laser deposition (PLD) techniques. Diode-like behavior with high short-circuit current (SSC ∼ 4 mA/cm2) and open-circuit voltage (OCV ∼ 0.22 V) was obtained under the illumination of about 1% of maximum solar energy. Impedance spectroscopy revealed that electrode/dielectric interface and grain-boundary conduction are mainly responsible for the photo-current. Electrode/dielectric interface, grain boundary impedance, and low-frequency ac conductivity change by almost three orders of magnitude under weak light. Relaxation time of the photo-carriers changes from 80 ms to 96 μs suggesting that with optimal collecting instruments, one should expect currents several orders higher.

Multiferroic bismuth ferrite-based materials for multifunctional applications: Ceramic bulks, thin films and nanostructures

“…Many parameters of ferroelectric and electrode materials can affect the photovoltaic output, including crystallographic orientations, 567 band gap, 75,573,555,575,596 electrical conductivity, 562 remnant polarization, 563 domain walls, 108 ferroelectric/electrode interface, 109 microstructure, 564 distance between two opposite electrodes. 565 With these understandings, some attempts have been made to enhance the photovoltaic efficiency of BFO-based devices [ Table 28], for example by band gap engineering, 75,573,555,575,596 selection of the interface and electrode materials, 71,386,[578][579][580][581][582][583][584][585][586] domain engineering, [587][588][589][590] construction of multilayer structure. 591,592 The overall photovoltaic efficiencies have been improved significantly over the past several years.…”

Electrical and piezoelectric properties of BiFeO3 thin films grown on SrxCa1−xRuO3-buffered SrTiO3 substrates

“…5 Domain walls and interfaces (grain boundaries and ferroelectric-electrode interfaces) are found to play important roles in the photovoltaic effects. 3,6,7 BFO is ferroelectric (FE) and antiferromagnetic (Anti-FM) in bulk samples, whereas it is FE and ferromagnetic (FM) in thin films and nanoparticles. [1][2][3][4][5][6][7][8][9][10] Moreover, the FE Curie temperature and Anti-FM Neel temperature of BFO are 810 C and 380 C, respectively, which are high enough for normal applications.…”

“…3,6,7 BFO is ferroelectric (FE) and antiferromagnetic (Anti-FM) in bulk samples, whereas it is FE and ferromagnetic (FM) in thin films and nanoparticles. [1][2][3][4][5][6][7][8][9][10] Moreover, the FE Curie temperature and Anti-FM Neel temperature of BFO are 810 C and 380 C, respectively, which are high enough for normal applications. 9,10 The appearance of FM behavior in BFO thin films is related to residual strain, which deforms the crystallographic structure from rhombohedral to tetragonal to some extent.…”

Effect of thickness on dielectric, ferroelectric, and optical properties of Ni substituted Pb(Zr0.2Ti0.8)O3 thin films

“…[1][2][3][14][15][16] Yang et al 2 have shown that photovoltaic effect in BiFeO 3 (BFO) thin films which have relatively small band gaps (E g $2.6-2.9 eV) arises from a unique mechanism, namely, structurally driven steps of the electrostatic potential at nanometer-scale in-plane domains and domain a)…”