Tag Archives: photovoltaics

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 .

Gentle plasma process for embedded silver-nanowire flexible transparent electrodes on temperature-sensitive polymer substrates

In the article “Gentle plasma process for embedded silver-nanowire flexible transparent electrodes on temperature-sensitive polymer substrates “ Lukas Kinner, Emil J W List-Kratochvil and Theodoros Dimopoulos investigate processing routes to obtain highly conductive and transparent electrodes of silver nanowires (AgNWs) on flexible polyethylene terephthalate (PET) substrate.*

Their study shows that both thermally stable polyimide, as well as temperature-sensitive PET can be used as flexible host substrates, combined with a gentle, AgNW plasma curing. This is possible by adjusting the fabrication sequence to accommodate the plasma curing step, depending on the host substrate. As a result, embedded AgNW electrodes, transferred from polyimide-to-PET and from PET-to-PET are obtained, with optical transmittance of ~80% (including the substrate) and sheet resistance of ~13 Ω/sq., similar to electrodes transferred from glass-to-glass substrates.*

The embedded AgNW electrodes on PET show superior performance in bending tests, as compared to indium-tin-oxide electrodes and can be easily combined with metal oxide films for device implementation. The introduced approach, involving low-cost flexible substrates, AgNW spray-coating and plasma curing, is compatible with high-throughput, roll-to-roll processing.*

The impact of the introduced processes concerns therefore applications where high-throughput production must be combined with sensitive, flexible substrates and ultra-thin device architectures, like OLEDs and organic- or perovskite-based photovoltaics.*

The sample surfaces were characterized with atomic force microscopy (AFM) in tapping mode, using high-resolution NANOSENSORS™ SuperSharpSilicon™ SSS-NCHR AFM probes.

Figure 5. from “Gentle plasma process for embedded silver-nanowire flexible transparent electrodes on temperature-sensitive polymer substrates “ by Lukas Kinner et al.: The sample surfaces were characterized with atomic force microscopy (AFM) in tapping mode, using high-resolution NANOSENSORS™ SuperSharpSilicon™ SSS-NCHR AFM probes.
AFM images of the AgNW electrodes for: (a) G2G SP, (b) G2G IP, (c) height profile for the dashed line marked in (b), (d) K2P SP, (e) P2P IP, (f) height profile for the dashed line marked in (e).
Figure 5. from “Gentle plasma process for embedded silver-nanowire flexible transparent electrodes on temperature-sensitive polymer substrates “ by Lukas Kinner et al.:
AFM images of the AgNW electrodes for: (a) G2G SP, (b) G2G IP, (c) height profile for the dashed line marked in (b), (d) K2P SP, (e) P2P IP, (f) height profile for the dashed line marked in (e).

*Lukas Kinner, Emil J W List-Kratochvil and Theodoros Dimopoulos
Gentle plasma process for embedded silver-nanowire flexible transparent electrodes on temperature-sensitive polymer substrates
Nanotechnology, Volume 31, Number 36 (2020)
DOI: https://doi.org/10.1088/1361-6528/ab97aa

Please follow this external link to read the full article: https://iopscience.iop.org/article/10.1088/1361-6528/ab97aa

Open Access: The article “Gentle plasma process for embedded silver-nanowire flexible transparent electrodes on temperature-sensitive polymer substrates” by Lukas Kinner, Emil J W List-Kratochvil and Theodoros Dimopoulos 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/.

Nontoxic pyrite iron sulfide nanocrystals as second electron acceptor in PTB7:PC71BM-based organic photovoltaic cells

Iron disulfide ( FeS2 ) is a natural earth-abundant and nontoxic material with possible applications in lithium batteries, transistors or photovoltaic (PV) devices. According to the analysis carried out by Wadia et al., among 23 semiconducting materials, FeS2 is the best candidate for the development of large-scale solar cells at low cost (<2 × 10−6 ¢/W). Furthermore, FeS2 exhibits excellent optoelectronic properties such as a band gap of 0.8 to 1.38 eV, a high optical absorption coefficient (2 × 105 cm−1), high carrier mobility (2 to 80 cm2/Vs) and a large charge carrier lifetime (200 ps). Therefore, FeS2 nanoparticles (NPs) can be a good alternative for PV applications.*

In “Nontoxic pyrite iron sulfide nanocrystals as second electron acceptor in PTB7:PC71BM-based organic photovoltaic cells “ Olivia Amargós-Reyes, José-Luis Maldonado, Omar Martínez-Alvarez, María-Elena Nicho, José Santos-Cruz, Juan Nicasio-Collazo, Irving Caballero-Quintana and Concepción Arenas-Arrocena report the synthesis of nontoxic pyrite iron sulfide ( FeS2 ) nanocrystals (NCs) using a two-pot method. Moreover, they study the influence of these NCs incorporated into the PTB7:PC71BM active layer of bulk-heterojunction ternary organic photovoltaic ( OPV ) cells.*

The AFM roughness images presented in this article were acquired in dynamic force mode using NANOSENSORS™ PointProbe® Plus PPP-NCLAu AFM probes.

Figure 7 from “Nontoxic pyrite iron sulfide nanocrystals as second electron acceptor in PTB7:PC71BM-based organic photovoltaic cells” shows the 2D (left) and 3D (right) AFM images of the OPVs with different concentrations of FeS2 recorded in the noncontact mode. The roughness of the OPV surface is increased gradually as the FeS2 concentration increases (Table 1 and Figure 7), such that traps for the charge carriers could occur and the leakage current could increase. Because of the FeS2 agglomerates, the OPV parameters tend to decrease, free charges cannot be efficiently extracted. This effect is most prominent for the OPV cells with 1% of FeS2 (Figure 7 and Supporting Information File 1, Figure S2d).
Figure 7 from “Nontoxic pyrite iron sulfide nanocrystals as second electron acceptor in PTB7:PC71BM-based organic photovoltaic cells” by Olivia Amargós-Reyes et al.:
2D (left) and 3D (right) AFM images of the OPVs with different concentrations of FeS2
(a) 0.0 wt %, b) 0.25 wt %, c) 0.5 wt % and d) 1.0 wt %) recorded in noncontact mode.

*Olivia Amargós-Reyes, José-Luis Maldonado, Omar Martínez-Alvarez, María-Elena Nicho, José Santos-Cruz, Juan Nicasio-Collazo, Irving Caballero-Quintana and Concepción Arenas-Arrocena
Nontoxic pyrite iron sulfide nanocrystals as second electron acceptor in PTB7:PC71BM-based organic photovoltaic cells
Beilstein Journal of . Nanotechnology 2019, 10, 2238–2250.
DOI: doi:10.3762/bjnano.10.216

Please follow this external link to read the full article: https://www.beilstein-journals.org/bjnano/articles/10/216#R65

Open Access: The article “Nontoxic pyrite iron sulfide nanocrystals as second electron acceptor in PTB7:PC71BM-based organic photovoltaic cells” by Olivia Amargós-Reyes, José-Luis Maldonado, Omar Martínez-Alvarez, María-Elena Nicho, José Santos-Cruz, Juan Nicasio-Collazo, Irving Caballero-Quintana and Concepción Arenas-Arrocena 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/.