Tag: perovskite materials

Kinetic-controlled Crystallization of α-FAPbI3 Inducing Preferred Crystallographic Orientation Enhances Photovoltaic Performance

Physical properties of the polycrystalline materials are mostly determined by their microstructure. As the crystallization process can determine the microstructure, the nucleation, and growth can also control whether the materials will be resulted in single crystalline or polycrystalline. Along with the morphological changes, anisotropic properties of the materials can also be controlled. *

As a result, preferential orientation with advanced optoelectronic properties can enhance the photovoltaic devices’ performance. *

Although incorporation of additives is one of the most studied methods to stabilize the photoactive α-phase of formamidinium lead tri-iodide (α-FAPbI3), no studies focus on how the additives affect the crystallization kinetics. *

In the article “Kinetic-Controlled Crystallization of α-FAPbI3 Inducing Preferred Crystallographic Orientation Enhances Photovoltaic Performance” along with the role of methylammonium chloride (MACl) as a “stabilizer” in the formation of α-FAPbI3, Sooeun Shin, Seongrok Seo, Seonghwa Jeong, Anir S. Sharbirin, Jeongyong Kim, Hyungju Ahn, Nam-Gyu Park and Hyunjung Shin point out the additional role as a “controller” in the crystallization kinetics. *

With microscopic observations, for example, electron backscatter diffraction and selected area electron diffraction, it is examined that higher concentration of MACl induces slower crystallization kinetics, resulting in larger grain size and [100] preferred orientation. *

Optoelectronic properties of [100] preferentially oriented grains with less non-radiative recombination, a longer lifetime of charge carriers, and lower photocurrent deviations in between each grain induce higher short-circuit current density (Jsc) and fill factor. *

Resulting MACl40 mol% attains the highest power conversion efficiency (PCE) of 24.1%.

The results provide observations of a direct correlation between the crystallographic orientation and device performance as it highlights the importance of crystallization kinetics resulting in desirable microstructures for device engineering. *

The electrical characterizations with atomic force microscopy (AFM) and conductive atomic force microscopy ( C-AFM) were done to measure the local conductance of FAPbI3 films. All measurements were performed under illumination (green LED) with a 1.3 V bias using a Pt-coated C-AFM probe (NanoWorld PlatinumIridium coated Pointprobe® CONTPt ). FTO was used for the conductive substrates. *

Conductive atomic force microscopy (C-AFM) indicated much more homogeneous photocurrent generation along the surface of (100) preferentially oriented layers. *

Figure 4 from Sooeun Shin et al. 2023 “Kinetic-Controlled Crystallization of α-FAPbI3 Inducing Preferred Crystallographic Orientation Enhances Photovoltaic Performance”:Electrical properties of (100)-oriented α-FAPbI3 thin films. a,b) Surface topography and photocurrent measurement by C-AFM of MACl10% and MACl40%. Measurements were taken under illumination (green LED) with a 1.3 V bias. Current images indicate that photocurrents were induced grain by grain, as each grain showed a distinct photocurrent. The photocurrent deviation for each grain is larger in MACl10% than in MACl40%, which shows a similar photocurrent grain by grain. c,d) Current line profile extracted from the current image (a and b). The standard deviation calculated from the magnitude of the photocurrent in each grain is displayed in the inset (0.019 and 0.014 nA for MACl10% and MACl40%, respectively). A low photocurrent was exhibited at the grain boundaries in both MACl10% and MACl40%. The dark areas measured within the current images are most likely distributed between grain edges. This may be caused by the formation of PbI2 or the loss of contact between the grain and the conducting substrate. NanoWorld PtIr5 coated Pointprobe® CONTPt AFM probes were used for the Electrical Characterization with conductive Atomic Force Microscopy (conductive-AFM, C-AFM) and for the atomic force microscopy.
Figure 4 from Sooeun Shin et al. 2023 “Kinetic-Controlled Crystallization of α-FAPbI3 Inducing Preferred Crystallographic Orientation Enhances Photovoltaic Performance”:
Electrical properties of (100)-oriented α-FAPbI3 thin films. a,b) Surface topography and photocurrent measurement by C-AFM of MACl10% and MACl40%. Measurements were taken under illumination (green LED) with a 1.3 V bias. Current images indicate that photocurrents were induced grain by grain, as each grain showed a distinct photocurrent. The photocurrent deviation for each grain is larger in MACl10% than in MACl40%, which shows a similar photocurrent grain by grain. c,d) Current line profile extracted from the current image (a and b). The standard deviation calculated from the magnitude of the photocurrent in each grain is displayed in the inset (0.019 and 0.014 nA for MACl10% and MACl40%, respectively). A low photocurrent was exhibited at the grain boundaries in both MACl10% and MACl40%. The dark areas measured within the current images are most likely distributed between grain edges. This may be caused by the formation of PbI2 or the loss of contact between the grain and the conducting substrate.

*Sooeun Shin, Seongrok Seo, Seonghwa Jeong, Anir S. Sharbirin, Jeongyong Kim, Hyungju Ahn, Nam-Gyu Park and Hyunjung Shin
Kinetic-Controlled Crystallization of α-FAPbI3 Inducing Preferred Crystallographic Orientation Enhances Photovoltaic Performance
Advanced Science, Volume 10, Issue 14, May 17, 2023, 2300798
DOI: https://doi.org/10.1002/advs.202300798

Open Access The article “Kinetic-Controlled Crystallization of α-FAPbI3 Inducing Preferred Crystallographic Orientation Enhances Photovoltaic Performance” Sooeun Shin, Seongrok Seo, Seonghwa Jeong, Anir S. Sharbirin, Jeongyong Kim, Hyungju Ahn, Nam-Gyu Park and Hyunjung Shin 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/.

Quantification of electron accumulation at grain boundaries in perovskite polycrystalline films by correlative infrared-spectroscopic nanoimaging and Kelvin probe force microscopy

Organic-inorganic halide perovskites are materials of high interest for the development of solar cells.

Learning more about the relationship between the electrical properties and the chemical compositions of perovskite at the nanoscale can help to understand how the interrelations of both can affect device performance and contribute to an understanding on how to best design perovskite active layer structures.*

For the article “Quantification of electron accumulation at grain boundaries in perovskite polycrystalline films by correlative infrared-spectroscopic nanoimaging and Kelvin probe force microscopy” Ting-Xiao Qin, En-Ming You, Mao-Xin Zhang, Peng Zheng, Xiao-Feng Huang, Song-Yuan Ding, Bing-Wei Mao and Zhong-Qun Tian used correlative infrared-spectroscopic nanoimaging ( IR-spectroscopy ) by scattering-type scanning near-field optical microscopy ( s-SNOM ) and Kelvin probe force microscopy ( KPFM ) to contribute to the discussion whether nanometer-sized grain boundaries (GBs) in polycrystalline perovskite films play a positive or negative role in solar cell performance.*

The integrated KPFM and s-SNOM measurements were performed by the authors to acquire the surface potential and infrared near-field image simultaneously through a single-pass scan and thereby learn more about the relationships between the electrical properties and spectral information at the grain boundaries of the investigated material ( polycrystalline CH3NH3Pbl3 perovskite films ).*

The results of the correlated s-SNOM and KPFM imaging presented in the article show that the electron accumulations are enhanced at the grain boundaries (GBs) of the investigated polycrystalline perovskite film, particularly under light illumination which would assist in electron-hole separation and therefore would be a positive influence on the performance of the solar cell.*

NanoWorld conductive platinum-iridium coated Arrow AFM probes ( Arrow-NCPt ) were used to perform the s-SNOM IR imaging.

Figure 4 from “Quantification of electron accumulation at grain boundaries in perovskite polycrystalline films by correlative infrared-spectroscopic nanoimaging and Kelvin probe force microscopy” by Ting-Xiao Qin et al. Correlative KPFM and s-SNOM nanoimaging on perovskite. a AFM topography (1 μm × 1 μm); b Contact potential difference (CPD); and c simultaneously acquired infrared near-field image; d one-dimensional line profiles of the topography, CPD and infrared near-field amplitude along the white dashed lines marked in a–c. The scale bars are 200 nm. NanoWorld Arrow-NCPt AFM probes were used to perform the s-SNOM IR imaging
Figure 4 from “Quantification of electron accumulation at grain boundaries in perovskite polycrystalline films by correlative infrared-spectroscopic nanoimaging and Kelvin probe force microscopy” by Ting-Xiao Qin  et al.
Correlative KPFM and s-SNOM nanoimaging on perovskite.
a AFM topography (1 μm × 1 μm); b Contact potential difference (CPD); and c simultaneously acquired infrared near-field image; d one-dimensional line profiles of the topography, CPD and infrared near-field amplitude along the white dashed lines marked in a–c. The scale bars are 200 nm.

*Ting-Xiao Qin, En-Ming You, Mao-Xin Zhang, Peng Zheng, Xiao-Feng Huang, Song-Yuan Ding, Bing-Wei Mao and Zhong-Qun Tian
Quantification of electron accumulation at grain boundaries in perovskite polycrystalline films by correlative infrared-spectroscopic nanoimaging and Kelvin probe force microscopy
Light: Science & Applications volume 10, Article number: 84 (2021)
DOI: https://doi.org/10.1038/s41377-021-00524-7

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Open Access : The article “Quantification of electron accumulation at grain boundaries in perovskite polycrystalline films by correlative infrared-spectroscopic nanoimaging and Kelvin probe force microscopy” by Ting-Xiao Qin, En-Ming You, Mao-Xin Zhang, Peng Zheng, Xiao-Feng Huang, Song-Yuan Ding, Bing-Wei Mao and Zhong-Qun Tian 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/.