Season’s Greetings from NANOSENSORS AFM probes

The reindeer are back in the park! This is a sure sign that it is again time to wish all users of our AFM probes Happy Holidays!

This has been a difficult year for many among us. Take care of yourselves. We are looking forward to a new year with better news together with you.

The reindeer are back in the park! Happy Holidays to all of you!

Nanoscale Charge Accumulation and Its Effect on Carrier Dynamics in Tri-cation Perovskite Structures

Nanoscale investigations by scanning probe microscopy have provided major contributions to the rapid development of organic–inorganic halide perovskites (OIHP) as optoelectronic devices. Further improvement of device level properties requires a deeper understanding of the performance-limiting mechanisms such as ion migration, phase segregation, and their effects on charge extraction both at the nano- and macroscale.*

In the article “Nanoscale Charge Accumulation and Its Effect on Carrier Dynamics in Tri-cation Perovskite Structures” David Toth, Bekele Hailegnaw, Filipe Richheimer, Fernando A. Castro, Ferry Kienberger, Markus C. Scharber, Sebastian Wood and Georg Gramse describe how they studied the dynamic electrical response of Cs0.05(FA0.83MA0.17)0.95PbI3–xBrx perovskite structures by employing conventional and microsecond time-resolved open-loop Kelvin probe force microscopy (KPFM).*

Their results indicate strong negative charge carrier trapping upon illumination and very slow (>1 s) relaxation of charges at the grain boundaries. The fast electronic recombination and transport dynamics on the microsecond scale probed by time-resolved open-loop KPFM show diffusion of charge carriers toward grain boundaries and indicate locally higher recombination rates because of intrinsic compositional heterogeneity. The nanoscale electrostatic effects revealed are summarized in a collective model for mixed-halide CsFAMA. Results on multilayer solar cell structures draw direct relations between nanoscale ionic transport, charge accumulation, recombination properties, and the final device performance.*

The author’s findings extend the current understanding of complex charge carrier dynamics in stable multication OIHP structures.*

NANOSENSORS™ Platinum Silicide AFM Probes of the PtSi-CONT type (nominal resonance frequency 13 kHz, nominal force constant 0.2 N/m) were used for the measurements described in the research article cited above. *

Figure 3. from “Nanoscale Charge Accumulation and Its Effect on Carrier Dynamics in Tri-cation Perovskite Structures” by David Toth et al:
Initial dark and relaxed closed-loop KPFM analysis of CsFAMAPbBrI. (a) Topography channel plotting surface height. (b) KPFM image prior to light pulse plotting Vcpd. (c) KPFM image seconds after the light pulse plotting Vcpd. (d) 3D topography overlaid with the calculated ΔVcpd map. (e) Histograms of before and after Vcpd maps separated into grain and GB responses. The double arrows indicate the difference between the mean values of the distributions. NANOSENSORS™ Platinumum-Silicide PtSi-CONT AFM probes were used for the KPFM measurements.

Figure 3. from “Nanoscale Charge Accumulation and Its Effect on Carrier Dynamics in Tri-cation Perovskite Structures” by David Toth et al:
Initial dark and relaxed closed-loop KPFM analysis of CsFAMAPbBrI. (a) Topography channel plotting surface height. (b) KPFM image prior to light pulse plotting Vcpd. (c) KPFM image seconds after the light pulse plotting Vcpd. (d) 3D topography overlaid with the calculated ΔVcpd map. (e) Histograms of before and after Vcpd maps separated into grain and GB responses. The double arrows indicate the difference between the mean values of the distributions.

*David Toth, Bekele Hailegnaw, Filipe Richheimer, Fernando A. Castro, Ferry Kienberger, Markus C. Scharber, Sebastian Wood and Georg Gramse
Nanoscale Charge Accumulation and Its Effect on Carrier Dynamics in Tri-cation Perovskite Structures
ACS Appl. Mater. Interfaces 2020, 12, 42, 48057–48066
DOI: https://doi.org/10.1021/acsami.0c10641

Please follow this external link to read the full article: https://pubs.acs.org/doi/abs/10.1021/acsami.0c10641

Open Access The article “Nanoscale Charge Accumulation and Its Effect on Carrier Dynamics in Tri-cation Perovskite Structures” by David Toth, Bekele Hailegnaw, Filipe Richheimer, Fernando A. Castro, Ferry Kienberger, Markus C. Scharber, Sebastian Wood and Georg Gramse is licensed under a ACS AuthorChoice  – 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 http://creativecommons.org/licenses/by/4.0/. Further permissions related to the material excerpted above should be directed to the ACS .

Yeast Nanometric Scale Oscillations Highlights Fibronectin Induced Changes in C. Albicans

Yeast resistance to antifungal drugs is a major public health issue. Fungal adhesion onto the host mucosal surface is still a partially unknown phenomenon that is modulated by several actors among which fibronectin plays an important role. Targeting the yeast adhesion onto the mucosal surface could lead to potentially highly efficient treatments. *

In the article “Yeast Nanometric Scale Oscillations Highlights Fibronectin Induced Changes in C. Albicans” Anne-Céline Kohler, Leonardo Venturelli, Abhilash Kannan, Dominique Sanglard, Giovanni Dietler, Ronnie Willaert and Sandor Kasas, explore the effect of fibronectin on the nanomotion pattern of different Candida albicans strains by atomic force microscopy ( AFM )-based nanomotion detection and correlated the cellular oscillations to the yeast adhesion onto epithelial cells. *

The authors demonstrate the ability of nanomotion detection to monitor in real time and in a label-free manner cellular activity changes induced by interacting ligands. Activity changes induced by increasing glucose concentration were observed for Escherichia coli in a previous study. This technique opens novel avenues to detect cellular activation or inhibition induced by ligand–receptor interactions. *

The AFM cantilever oscillations were collected in real time using an by the authors in-house developed nanomotion detection device with NANOSENSORS™ tipless uniqprobe SD-qp-CONT-TL AFM probes from the NANOSENSORS Special Developments List. *

The SD-qp-CONT-TL AFM cantilevers with a nominal spring constant of 0.1 N/m and an average resonant peak in liquids of 8 kHz, were coated with 2 mg/mL of concanavalin A (Con A) for 30 min at room temperature. After removing the excess of Con A, the yeast cells were placed in contact with the AFM cantilever for 1 h at room temperature to allow them to attach to its surface. Poorly attached C. albicans cells were removed by washing gently with YPD medium. Finally, the C. albicans covered AFM cantilever was inserted into the analysis chamber containing 2 mL of filtered (0.2 µm syringe filter, YPD medium. The measurements were performed at room temperature in YPD medium and in YPD medium containing 25 µg/mL of fibronectin. Fibronectin was directly added inside the chip reservoir. For the experiments performed with antifungals, caspofungin was diluted in the YPD present in the analysis chamber to reach a final concentration of 100 µg/mL. *

Supplementary Figure S2 from “Yeast Nanometric Scale Oscillations Highlights Fibronectin Induced Changes in C. Albicans” by Anne-Céline Kohler et al.:
Density of yeast cells on cantilever at the start of the experiment (A) and at the end of the experiment (B). The size of the AFM cantilever is 40 by 130 μm. NANOSENSORS tipless uniqprobe SD-qp-CONT-TL AFM probes from the NANOSENSORS Special Developments List were used in the in-house developed nanomotion detection device.
Supplementary Figure S2 from “Yeast Nanometric Scale Oscillations Highlights Fibronectin Induced Changes in C. Albicans” by Anne-Céline Kohler et al.:
Density of yeast cells on cantilever at the start of the experiment (A) and at the end of the experiment (B). The size of the AFM cantilever is 40 by 130 μm.

*Anne-Céline Kohler, Leonardo Venturelli, Abhilash Kannan, Dominique Sanglard, Giovanni Dietler, Ronnie Willaert and Sandor Kasas
Yeast Nanometric Scale Oscillations Highlights Fibronectin Induced Changes in C. Albicans
Fermentation 2020, 6(1), 28
DOI: https://doi.org/10.3390/fermentation6010028

Please follow this external link to read the full article: https://www.mdpi.com/2311-5637/6/1/28/htm#B5-fermentation-06-00028

Open Access The article “Yeast Nanometric Scale Oscillations Highlights Fibronectin Induced Changes in C. Albicans” by Anne-Céline Kohler, Leonardo Venturelli, Abhilash Kannan, Dominique Sanglard, Giovanni Dietler, Ronnie Willaert and Sandor Kasas 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 http://creativecommons.org/licenses/by/4.0/.