Quantitative Image Analysis of Fractal‐Like Thin Films of Organic Semiconductors

Zhu, Weikun; Mohammadi, Erfan; Diao, Ying

doi:10.1002/polb.24875

Cited by 12 publications

(9 citation statements)

References 49 publications

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“…While the low surface energy of the PTS might have lowered the Gibbs' free energy for nucleation on PTS substrates compared to plasma treated SiO 2 ,13 the monolayer film was still riddled with voids, giving a film coverage of ≈86%. Quantitatively, we determined using an image analysis protocol we developed18 that the fractal dimension of the monolayer films on IL is 2, which significantly decreases to 1.33 ± 0.06 and 1.48 ± 0.05 for those on plasma SiO 2 and PTS, respectively.…”

Section: Resultsmentioning

confidence: 99%

Printing 2D Conjugated Polymer Monolayers and Their Distinct Electronic Properties

Kafle

Zhang

Schorr

et al. 2020

Adv Funct Materials

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Recently, 2D monolayer films of conjugated polymers have gained increasing attention owing to the preeminence of 2D inorganic films that exhibit unique optoelectronic and mechanical properties compared to their bulk analogs. Despite numerous efforts, crystallization of semiconducting polymers into highly ordered 2D monolayer films still remains challenging. Herein, a dynamic‐template‐assisted meniscus‐guided coating is utilized to fabricate continuous, highly ordered 2D monolayer films of conjugated polymers over a centimeter scale with enhanced backbone π–π stacking. In contrast, monolayer films printed on solid substrates confer upon the 1D fiber networks strong alkyl side‐chain stacking at the expense of backbone packing. From single‐layers to multilayers, the polymer π‐stacks change from edge‐on to bimodal orientation as the film thickness reaches ≈20 nm. Spectroscopic and cyclic voltammetry analysis reveals an abrupt increase in J‐aggregation and absorption coefficient and a decrease in bandgap and highest occupied molecular orbital level until critical thickness, possibly arising from the straightened polymer backbone. This is corroborated by an abrupt increase in hole mobility with film thickness, reaching a maximum of 0.7 cm2 V−1 s−1 near the critical thickness. Finally, fabrication of chemical sensors incorporating polymer films of various thicknesses is demonstrated, and an ultrahigh sensitivity of the ≈7 nm thick ultrathin film (bilayers) to 1 ppb ammonia is shown.

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Section: Resultsmentioning

confidence: 99%

Printing 2D Conjugated Polymer Monolayers and Their Distinct Electronic Properties

Kafle

Zhang

Schorr

et al. 2020

Adv Funct Materials

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“…Image analysis was performed on the thin films of APIs using a MATLAB code to find the exact area exposed to water. 39 Film Thickness Measurement. The thickness of API films was measured using Asylum Cypher AFM with Tap300AI-G tapping mode AFM tips.…”

Section: ■ Experimental Methodsmentioning

confidence: 99%

“…The morphology of the solution coated thin films was visualized using a cross-polarized optical microscope (Nikon ECLIPSE Ci-POL) and imaging software (NIS-Elements). Image analysis was performed on the thin films of APIs using a MATLAB code to find the exact area exposed to water …”

Section: Experimental Methodsmentioning

confidence: 99%

Drastic Modulation of Molecular Packing and Intrinsic Dissolution Rates by Meniscus-Guided Coating of Extremely Confined Pharmaceutical Thin Films

Kafle

Sanghavi

Khasbaatar

et al. 2021

ACS Appl. Mater. Interfaces

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Nanosizing has emerged as one of the most effective formulation strategies for enhancement of dissolution properties of active pharmaceutical ingredients (APIs). In addition to enhancing the specific area of the dissolving solids, nanosizing can also capture and stabilize the metastable form of the API, which can further enhance the solubility by drastic modulation of surface energies. Herein, we employ meniscus-guided coating to fabricate nanothin films of three APIs that show anticancer properties and are poorly soluble:10-HCPT, SN-38, and amonafide. By modulating the coating speed, we systematically deposited the APIs in films ranging from ∼200 nm thickness to extreme confinement of ∼10 nm (<10 molecular layers). In all three APIs, we observe a general order-to-disorder transition with semicrystalline (10-HCPT and amonafide) or amorphous (SN-38) form of API solids trapped in thin films when the thickness decreases below a critical value of ∼25–30 nm. The existence of a critical thickness highlights the importance of nanoconfinement in tuning molecular packing. In the case of 10-HCPT, we demonstrate that the disordered form of the API occurs largely due to lack of incorporation of water molecules in thinner films below the critical thickness, thereby disrupting the three-dimensional hydrogen-bonded network held by water molecules. We further developed a dissolution model that predicts variation of the intrinsic dissolution rate (IDR) with API film thickness, which also closely matched with experimental results. We achieved drastic improvement in the IDR of ∼240% in 10-HCPT by decreasing film thickness alone. Further leveraging the order-to-disorder transition led to 2570% modulation of the IDR for amonafide. Our work demonstrates, for the first time, opportunities to largely modulate API dissolution by precisely controlling the dimensionality of thin films.

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“…Talu S. et al [32] 2016 Co/CP/X Electrochemistry SEM Feng F. et al [76] 2017 MgO EPSAD AFM Nasehnejad M. et al [81] 2017 silver electrodeposition sputtering AFM Soumya S. et al [43] 2017 ZnS PLD AFM Yadav R. P. et al [91] 2017 ZnO atom beam sputtering AFM Talu S. et al [73] 2017 Ag-Cu magnetron sputtering AFM Talu S. et al [142] 2017 carbon-nickel magnetron sputtering AFM Talu S. et al [165] 2017 contact lenses polished AFM Talu S. et al [143] 2017 filler nanoparticles spin-coating AFM Talu S. et al [144] 2017 Ni NPs@a-C CVD AFM Sani Z. K. et al [145] 2017 [155] 2019 C8-BTBT meniscus-guided coating OM Ghosh K. et al [86] 2019 ZnO sol-gel spin-coating AFM Mwema F. M. et al [156] 2019 Al magnetron sputtering AFM Pedro, G.d.C. et al [157] 2019 chlorophyll (Chl) casting & drying OM Talu S. et al [63] 2020 Ag-Cu magnetron sputtering AFM Jafari A. et al [158] 2020 copper oxide magnetron sputtering AFM Yildiz K. et al [159] 2020 montmorillonite cast OM Aminirastabi H. et al [160] 2020 BaTiO 3 sol-gel -Yang L. et al [161] 2021 Pt electroless plating SEM Jiang Y. et al [163] 2021 MoS 2 CVD OM Jiang H. et al [15] 2021 metallic glass ion beam deposition STEM Romaguera Y. et al [164] 2021 GdMnO 3 spin-coating AFM…”

Section: Abbreviations Appendix Amentioning

confidence: 99%

Fractal Analysis on Surface Topography of Thin Films: A Review

et al. 2022

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The topographies of various surfaces have been studied in many fields due to the significant influence that surfaces have on the practical performance of a given sample. A comprehensive evaluation requires the assistance of fractal analysis, which is of significant importance for modern science and technology. Due to the deep insights of fractal theory, fractal analysis on surface topographies has been widely applied and recommended. In this paper, the remarkable uprising in recent decades of fractal analysis on the surfaces of thin films, an essential domain of surface engineering, is reviewed. By summarizing the methods used to calculate fractal dimension and the deposition techniques of thin films, the results and trends of fractal analysis are associated with the microstructure, deposition parameters, etc. and this contributes profoundly to exploring the mechanism of film growth under different conditions. Choosing appropriate methods of surface characterization and calculation methods to study diverse surfaces is the main challenge of current research on thin film surface topography by using fractal theory. Prospective developing trends are proposed based on the data extraction and statistics of the published literature in this field.

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Quantitative Image Analysis of Fractal‐Like Thin Films of Organic Semiconductors

Cited by 12 publications

References 49 publications

Printing 2D Conjugated Polymer Monolayers and Their Distinct Electronic Properties

Printing 2D Conjugated Polymer Monolayers and Their Distinct Electronic Properties

Drastic Modulation of Molecular Packing and Intrinsic Dissolution Rates by Meniscus-Guided Coating of Extremely Confined Pharmaceutical Thin Films

Fractal Analysis on Surface Topography of Thin Films: A Review

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