Active self-assembly of piezoelectric biomolecular films via synergistic nanoconfinement and in-situ poling

Piezoelectric biomaterials have attracted great attention owing to the recent recognition of the impact of piezoelectricity on biological systems and their potential applications in implantable sensors, actuators, and energy harvesters. However, their practical use is hindered by the weak piezoelectric effect caused by the random polarization of biomaterials and the challenges of large-scale alignment of domains.*

In the article “Active self-assembly of piezoelectric biomolecular films via synergistic nanoconfinement and in-situ poling” Zhuomin Zhang, Xuemu Li, Zehua Peng, Xiaodong Yan, Shiyuan Liu, Ying Hong, Yao Shan, Xiaote Xu, Lihan Jin, Bingren Liu, Xinyu Zhang, Yu Chai, Shujun Zhang, Alex K.-Y. Jen and Zhengbao Yang present an active self-assembly strategy to tailor piezoelectric biomaterial thin films.*

The nanoconfinement-induced homogeneous nucleation overcomes the interfacial dependency and allows the electric field applied in-situ to align crystal grains across the entire film. The β-glycine films exhibit an enhanced piezoelectric strain coefficient of 11.2 pm V−1 and an exceptional piezoelectric voltage coefficient of 252 × 10−3 Vm N−1. Of particular significance is that the nanoconfinement effect greatly improves the thermostability before melting (192 °C). *

This finding offers a generally applicable strategy for constructing high-performance large-sized piezoelectric bio-organic materials for biological and medical microdevices.*

The piezoelectric properties of the as-prepared β-glycine nanocrystalline films were evaluated by piezoresponse force microscopy (PFM) measurements.*

For all piezoresponse force microscopy (PFM) measurements and SKPM (scanning Kelvin probe force microscopy) measurements mentioned in this article, conductive NanoWorld Arrow-EFM AFM probes with PtIr coating on both AFM cantilever and AFM tip were used. The nominal resonance frequency and the nominal stiffness of the AFM probe are 75 kHz and 2.8 N m−1, respectively.

Figure 3 from “Active self-assembly of piezoelectric biomolecular films via synergistic nanoconfinement and in-situ poling” by Zhuomin Zhang et al.:PFM measurements and polarization alignment studies of β-glycine nanocrystalline films. a The PFM OOP amplitude mapping overlaid on the 3D topography of as-prepared films in a 1.5 × 1.5 µm2 area. The applied AC voltage is 2 V. b The corresponding PFM OOP phase mapping overlaid on the 3D topography. c Histogram calculated from the PFM OOP phase mapping in (b) showing that the β-glycine nanocrystalline films are dominated by domains with the unique polarization direction. d PFM OOP phase mapping of the β-glycine microcrystals obtained by electrohydrodynamic focusing deposition through heterogeneous nucleation. e Histogram calculated from the phase mapping in (d). f Comparison of statistics of the piezoelectric phase for the as-prepared β-glycine nanocrystalline films via synergistic nanoconfinement and in-situ poling (left), and β-glycine microcrystals grown by heterogeneous nucleation in the absence of nanoconfinement effect (right). NanoWorld conductive Arrow-EFM AFM probes were used for the piezoresponse force microscopy (PFM) and scanning Kelvin probe force microscopy (SKPFM) measurements mentioned in this article.
Figure 3 from “Active self-assembly of piezoelectric biomolecular films via synergistic nanoconfinement and in-situ poling” by Zhuomin Zhang et al.:
PFM measurements and polarization alignment studies of β-glycine nanocrystalline films.
a The PFM OOP amplitude mapping overlaid on the 3D topography of as-prepared films in a 1.5 × 1.5 µm2 area. The applied AC voltage is 2 V. b The corresponding PFM OOP phase mapping overlaid on the 3D topography. c Histogram calculated from the PFM OOP phase mapping in (b) showing that the β-glycine nanocrystalline films are dominated by domains with the unique polarization direction. d PFM OOP phase mapping of the β-glycine microcrystals obtained by electrohydrodynamic focusing deposition through heterogeneous nucleation. e Histogram calculated from the phase mapping in (d). f Comparison of statistics of the piezoelectric phase for the as-prepared β-glycine nanocrystalline films via synergistic nanoconfinement and in-situ poling (left), and β-glycine microcrystals grown by heterogeneous nucleation in the absence of nanoconfinement effect (right).

*Zhuomin Zhang, Xuemu Li, Zehua Peng, Xiaodong Yan, Shiyuan Liu, Ying Hong, Yao Shan, Xiaote Xu, Lihan Jin, Bingren Liu, Xinyu Zhang, Yu Chai, Shujun Zhang, Alex K.-Y. Jen and Zhengbao Yang
Active self-assembly of piezoelectric biomolecular films via synergistic nanoconfinement and in-situ poling
Nature Communications volume 14, Article number: 4094 (2023)
DOI: https://doi.org/10.1038/s41467-023-39692-y

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The article “Active self-assembly of piezoelectric biomolecular films via synergistic nanoconfinement and in-situ poling” by Zhuomin Zhang, Xuemu Li, Zehua Peng, Xiaodong Yan, Shiyuan Liu, Ying Hong, Yao Shan, Xiaote Xu, Lihan Jin, Bingren Liu, Xinyu Zhang, Yu Chai, Shujun Zhang, Alex K.-Y. Jen and Zhengbao Yang is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third-party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/.

Cross-sectional Kelvin probe force microscopy on III–V epitaxial multilayer stacks: challenges and perspectives

The development of photovoltaic (PV) technologies has progressed significantly over the past twenty years as a result of considerable advancements in solar cell device engineering and material science. *

As a consequence, solar cells have turned into complex structures containing numerous layers and interfaces. The capability to conduct local investigations at the nanoscale level that provide information on the electrical properties of materials and along physical interfaces is becoming crucial for solar photovoltaic device efficiency improvement. *

The capability to conduct local investigations at the nanoscale level that provide information on the electrical properties of materials and along physical interfaces is becoming crucial for solar photovoltaic device efficiency improvement. *

Multilayer III–V-based solar cells are complex devices consisting of many layers and interfaces. *

The study and the comprehension of the mechanisms that take place at the interfaces is crucial for efficiency improvement. *

Electrical measurements based on scanning probe microscopy (SPM) allow for the analysis of two-dimensional (2D) features at the surface and along a physical cross section of nanoscale semiconductor structures. *

Among the wide variety of SPM techniques available, Kelvin probe force microscopy (KPFM) is an application of the atomic force microscope (AFM) for the evaluation of the surface potential with nanometric resolution. KPFM is a valuable investigative approach for the study of work functions via the measurement of the contact potential difference VCPD, that is, the difference between the electrostatic potential at the surface of the investigated structure and that of the KPFM probe. *

In the article “Cross-sectional Kelvin probe force microscopy on III–V epitaxial multilayer stacks: challenges and perspectives” Mattia da Lisca, José Alvarez, James P. Connolly, Nicolas Vaissiere, Karim Mekhazni, Jean Decobert and Jean-Paul Kleider apply frequency-modulated Kelvin probe force microscopy (FM-KPFM) under ambient conditions to investigate the capability of this technique for the analysis of an InP/GaInAs(P) multilayer stack. *

KPFM reveals a strong dependence on the local doping concentration, allowing for the detection of the surface potential of layers with a resolution as low as 20 nm. *

The analysis of the surface potential allowed for the identification of space charge regions and, thus, the presence of several junctions along the stack. Furthermore, a contrast enhancement in the surface potential image was observed when KPFM was performed under illumination, which is analysed in terms of the reduction of surface band bending induced by surface defects by photogenerated carrier distributions. The analysis of the KPFM data was assisted by means of theoretical modelling simulating the energy bands profile and KPFM measurements. *

KPFM was performed using a scanning probe microscopy system under ambient conditions and operated in the frequency-modulated KPFM (FM-KPFM) mode using a two-pass scanning mode, where the second pass was performed at a constant distance of 10 nm from the sample surface. *

The FM-KPFM mode was chosen over the amplitude-modulation mode (AM-KPFM) since it is well known that it provides better spatial resolution. In particular, in AM-KPFM the electrical force between the tip and the sample is directly evaluated, whereas in FM-KPFM the gradient of the force is analysed. As a result, FM-KPFM is more sensitive to local tip apex–sample surface interactions; therefore, long-range electrostatic interactions of the cantilever are reduced, as well as the effect of parasitic capacitances. Additionally, in FM-KPFM, surface potential measurements are less dependent on the lift-height tip–sample distance than in AM-KPFM since this mode is less sensitive to static offsets induced by capacitive coupling or crosstalk. *

The laser beam deflection system in the author’s AFM employs a laser wavelength of 1310 nm, which is well below the bandgap of the sample; therefore, the parasitic laser absorption, which may interfere with the KPFM measurement, is reduced to negligible levels. Highly doped NanoWorld n+-Si ARROW-EFM tips (typical AFM tip radius < 25 nm) with a conductive Pt/Ir coating at a typical resonance frequency of 75 kHz were used. *

Figure 4 from “Cross-sectional Kelvin probe force microscopy on III–V epitaxial multilayer stacks: challenges and perspectives” by Mattia da Lisca et al : KPFM measurement under ambient conditions on the surface cross section of the sample under illumination: (a) topography and (b) VCPD image. A vertical coloured bar is included to ease the identification of the different layers. The profile in (c) corresponds to the region identified by the dotted white segments in (b), each point of the profile (vertical) direction being an average of 207 points over a width of 0.7 μm along the x axis. Several regions along the structure have been highlighted using different colours (see text). The black arrow indicates the space charge region at the InP:nid/InP:Zn interface. Highly doped NanoWorld n+-Si ARROW-EFM AFM probes (typical AFM tip radius < 25 nm) with a conductive Pt/Ir coating at a typical resonance frequency of 75 kHz were used.
Figure 4 from “Cross-sectional Kelvin probe force microscopy on III–V epitaxial multilayer stacks: challenges and perspectives” by Mattia da Lisca et al :
KPFM measurement under ambient conditions on the surface cross section of the sample under illumination: (a) topography and (b) VCPD image. A vertical coloured bar is included to ease the identification of the different layers. The profile in (c) corresponds to the region identified by the dotted white segments in (b), each point of the profile (vertical) direction being an average of 207 points over a width of 0.7 μm along the x axis. Several regions along the structure have been highlighted using different colours (see text). The black arrow indicates the space charge region at the InP:nid/InP:Zn interface.

*Mattia da Lisca, José Alvarez, James P. Connolly, Nicolas Vaissiere, Karim Mekhazni, Jean Decobert and  Jean-Paul Kleider
Cross-sectional Kelvin probe force microscopy on III–V epitaxial multilayer stacks: challenges and perspectives
Beilstein Journal of Nanotechnology 2023, 14, 725–737
DOI: https://doi.org/10.3762/bjnano.14.59

The article “Cross-sectional Kelvin probe force microscopy on III–V epitaxial multilayer stacks: challenges and perspectives” by Mattia da Lisca, José Alvarez, James P. Connolly, Nicolas Vaissiere, Karim Mekhazni, Jean Decobert and  Jean-Paul Kleider is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third-party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/.

Piezoelectric property of PZT nanofibers characterized by resonant piezo-force microscopy

Nano-piezoelectric materials such as 1D piezoelectric nanofibers, nanowires, and nanobelts have attracted a lot of research interest in recent years. *

Because of their active property that can transform strain energy into electricity, 1D piezoelectric nano-materials can be building blocks for nano-generators, strain sensors, acoustic sensors, force sensors, biosensors, self-powered drug delivery systems, piezoelectric transistors and other intelligent systems. *

The most important property of these active materials is their ability to convert mechanical energy into electrical energy and vice versa. *

Therefore, researchers started developing nano-sized piezoelectric materials in hope of achieving better piezoelectric properties. *

The characterization of these piezoelectric properties, especially measuring the piezoelectric strain coefficients, remains a challenge. *

The Atomic Force Microscopy (AFM)-based method to directly measure nano-materials’ piezoelectric strain coefficients is widely used.

However, several factors such as the extremely small piezoelectric deformation, the influence from the parasitic electrostatic force, and the environmental noise can make the measurement results questionable. *

In the article “Piezoelectric property of PZT nanofibers characterized by resonant piezo-force microscopy” Guitao Zhang, Xi Chen, Weihe Xu, Wei-Dong Yao, and Yong Shi address these issues by introducing a resonant piezo-force microscopy method and describing how it was used to accurately measure the piezoelectric deformation from 1D piezoelectric nanofibers. *

During the measurement the AFM tip was brought into contact with the piezoelectric sample and set to work close to the AFM tip’s first resonant frequency. *

The AFM probe used in this test was a platinum iridium coated NanoWorld Arrow-CONTPt (typical force constant 0.2 N/m, typical resonant frequency 14 KHz. The PtIr coating makes the AFM tip conductive and at the same time enhances the laser reflection from the detector facing side of the AFM cantilever to the photodetector. *

A lock-in amplifier was used to pick up the sample’s deformation signal at the testing frequency. By using this technique, the piezoelectric strain constant d33 of the Lead Zirconate Titanate (PZT) nanofiber with a diameter of 76 nm was measured. The result showed that d33 of this PZT nanofiber was around 387 pm/V. Meanwhile, by tracking the piezoelectric deformation phase image, domain structures inside PZT nanofibers were identified. *

Figure 5 from “Piezoelectric property of PZT nanofibers characterized by resonant piezo-force microscopy” by Guitao Zhang et al. : Piezoelectric deformation amplitude image from a PZT nanofiber on a silicon dioxide substrate (a) and its cross-sectional view along the horizontal direction (b). Conductive NanoWorld Arrow-CONTPt AFM probes were used for the resonant piezo-force microscopy
Figure 5 from “Piezoelectric property of PZT nanofibers characterized by resonant piezo-force microscopy” by Guitao Zhang et al. :
Piezoelectric deformation amplitude image from a PZT nanofiber on a silicon dioxide substrate (a) and its cross-sectional view along the horizontal direction (b).

 

Figure 6 from “Piezoelectric property of PZT nanofibers characterized by resonant piezo-force microscopy” by Guitao Zhang et al. : (a) Piezoelectric deformation phase image from a PZT nanofiber on the silicon dioxide substrate and its 3D image (b). NanoWorld Arrow-CONTPt platinum iridium 5 coated AFM probes were used.
Figure 6 from “Piezoelectric property of PZT nanofibers characterized by resonant piezo-force microscopy” by Guitao Zhang et al. :
(a) Piezoelectric deformation phase image from a PZT nanofiber on the silicon dioxide substrate and its 3D image (b).

*Guitao Zhang, Xi Chen, Weihe Xu, Wei-Dong Yao and Yong Shi
Piezoelectric property of PZT nanofibers characterized by resonant piezo-force microscopy
AIP Advances 12, 035203 (2022)
DOI: https://doi.org/10.1063/5.0081109

The article “Piezoelectric property of PZT nanofibers characterized by resonant piezo-force microscopy” by Guitao Zhang, Xi Chen, Weihe Xu, Wei-Dong Yao and Yong Shi is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/.