Bulk-Controlled Photovoltaic Effect in Nanometer-Thick Ferroelectric Pb(Zr_0.2Ti_0.8)O₃ Thin Films and the Role of Domain Walls

Abstract

Photovoltaic effect in ferroelectrics can be considered as a sum of two dominant contributions, that is, arising from the ferroelectric/metal junctions and from the bulk of the ferroelectrics. In the case of Pb­(Zr0.2Ti0.8)­O3, several studies have been devoted to analyze the contributions from the junctions and associated aspects such as barrier height. In this work, we elaborate on the contribution from the bulk, and the role of an inherent nano-sized entity, that is, domain walls. Systematic investigations were conducted with samples of different thicknesses (75–700 nm), which evidently also assisted in varying the proportion of domain walls. The open-circuit voltages scaled up with thickness in accordance with the bulk-driven photovoltaics phenomenology. Temperature-resolved measurements highlighted the influence of domain walls on the overall transport characteristics under light and dark conditions. Analysis of the spectral photoresponse unraveled the sub-band gap character of the domain walls and the prospective role in the overall photovoltaic effect.

Ultrahigh Bulk Photovoltaic Effect Responsivity in Thin Films: Unexpected Behavior in a Classic Ferroelectric Material

“…Several other reports of thin-film ferroelectric PV in the literature show a trend of increasing J-V nonlinearity with thinner films. [41][42][43] While in several cases, these effects were ascribed to heterojunctions; in light of our results for the BaTiO 3 films here, it is likely that in fact they are also due to the BPE-Schottky barrier mechanism.…”

Low-Temperature Induced Enhancement of Photoelectric Performance in Semiconducting Nanomaterials

“…Weng et al prepared a CdS/PbSe photovoltaic photodetector and then discovered that the cooling-enhanced cutoff wavelength expanded to near 7.0 μm due to the band energy component being changed by the temperature [ 19 ]. As depicted in Figure 2 d, the unique photovoltaic effect in ferroelectric materials like BiFeO 3 [ 70 , 94 , 95 , 96 , 97 , 98 ] and Pb(Zr,Ti)O 3 [ 52 , 99 ] inspired research on temperature-influenced bulk photovoltaic performance. The research of III-Vs and HgCdTe-based photodetectors significantly pushed forward the development of infrared sensing systems.…”

“…The position responsivity of ITO/Si has been researched by Qiao et al showing 7.47 mV/mm at 80 K. This is about 1.91 times of performance at 295 K [ 148 ], attributed to different Schottky barriers at various temperatures. Previous reports on the BPV effect in PbZr 0.2 Ti 0.8 O 3 (PZT) have observed increasing V oc and decreasing dark current due to the temperature-influenced resistance of the Schottky barrier at ferroelectric-electrode interfaces [ 52 ].…”

“…( c 2 ) Pb 1−x Sn x Se (adapted from [ 51 ], with permission from Wiley-VCH, 2015). ( d ) Ferroelectric ceramics (adapted from [ 52 ], with permission from the American Chemical Society, 2020). ( e ) Hg(Cd)Te (adapted from [ 53 ], with permission from the American Chemical Society, 2018).…”

Impact of Mn doping on the ferroelectric photovoltaic effect in multidomain BiFeO3 thin films under above-bandgap illumination

“…The bulk PV effect that arises from spatial inversion symmetry breaking in their polar crystal structures has been recognized as one of the origins of the unique PV responses of ferroelectric materials. [6][7][8][9] The bulk PV effect has been observed for various ferroelectric materials such as LiNbO 3 , 8,10,11) BaTiO 3 , [12][13][14] BiFeO 3 (BFO), 15,16) Pbbased perovskite oxides, 17,18) SbSI, 5,19) hybrid organic-inorganic materials, [20][21][22] and two-dimensional materials. 23,24) The shift current theory succeeded in reproducing photocurrents derived from the bulk PV effect induced by band-band photoexcitation.…”