Mol2Net-04 Sb 2 S 3 thin films: effect of PEI polymer substrate on - PDF document

Mol2Net-04 , 2018 , BIOCHEMPHYS-01 (pages 1- x, type of paper, doi: xxx-xxxx http://sciforum.net/conference/mol2net-4 SciForum Mol2Net-04 Sb 2 S 3 thin films: effect of PEI polymer substrate on physical properties Sameh Ben Ameur 1, *, and Hajer Guermazi 1 1 Research Unit: Physics of insulators and semi insulator materials, Faculty of Science of Sfax, Road of Soukra Km 3.5, B.P: 1171 3000 Sfax, University of Sfax, Tunisia, hajer.guermazi@gmail.com * E-Mail: sameh.benameur@yahoo.fr; Tel.: +216-50-511-723 Abstract: The aim of this work is to highlight the substrate effects on physical properties of antimony trisulphide (Sb 2 S 3 ) thin films grown by simple chemical bath deposition. Sb 2 S 3 thin films were deposited on glass and flexible Polyetherimide (PEI) substrates using similar deposition conditions. X- ray diffraction results indicate that both Sb 2 S 3 /glass and Sb 2 S 3 /PEI thin films are polycrystalline with orthorhombic structure. It was found that their texture and structural parameters are strongly dependent on the substrate. In fact, Sb 2 S 3 growth on polymer substrate leads to an enhancement in surface roughness (RMS = 33 nm for Sb 2 S 3 /glass, and 116 nm for Sb 2 S 3 /PEI) and superhydrophobic character. This makes Sb 2 S 3 /PEI sought to be used in self-cleaning applications Keywords: Sb 2 S 3 thin films, PEI flexible substrate, Self-cleaning 1. Introduction Sb 2 S 3 is one of interesting metal temperature, deposition rate. As known, the chalcogenides. In fact, Sb 2 S 3 thin films are physical properties of thin films are affected widely used for various applications in the obviously by the process parameters such as the semiconductor industry for making infrared substrate nature [2]. Using thin films deposited detectors, diodes, high-reflecting dielectric films, on polymer flexible substrates received a great microwave devices, switching devices, absorber interest in progressing flexible electronic devices layer in different hetero-junction photovoltaic such as solar cell planer [3]. Flexibility and light structures and photocatalysts [1]. This weight are two great advantages to using plastic considerable attention is due to its suitable band substrates [4]. gap, high absorption coefficient, relatively non- In this work, PEI flexible polymer and glass toxic and earth-abundant constituents, simple substrates are employed for growth of Sb 2 S 3 thin composition (binary compound), and long-term films by simple CBD technique. The effect of stability (a natural mineral: stibnite). The growth, substrate nature on the physical properties was structure, and properties of a deposited thin film investigated. Our study was especially focused depend significantly on a number of factors, such on the microstructure, surface morphology and as the nature of the substrate, substrate hydrophobicity properties. 2. Results and Discussion Fig. 1 shows the XRD patterns of the Sb 2 S 3 thin other peaks related to impurities are observed films grown glass as well as on PEI substrates. which proves the high purity of Sb 2 S 3 binary The XRD pattern of the Sb 2 S 3 /PEI sample phase. It is clear that the substrate nature affects showed broad band-related to the amorphous significantly the general texture and notably the structure of the PEI polymer. The labeled peaks preferred orientation. Hence, the preferential in XRD were compared to the standard JCPDS growth orientation of the polycrystalline Sb 2 S 3 powder diffraction data set (78-1347). This thin films can be understood from the texture analysis revealed that these samples are coefficient TC (hkl) calculation using the following polycrystalline with orthorhombic structure. No relation:

Mol2Net , 2015 , 1( Section A, B, C, etc. ), 1- x, type of paper, doi: xxx-xxxx 2 sizes are found to be 138 nm and 63 nm for the I / I ( ) ( ) = hkl 0 hkl TC (1) ( )  Sb 2 S 3 /glass and Sb 2 S 3 /PEI, respectively. Also, − hkl 1 N I / I ( ) ( ) hkl 0 hkl the structural defects are computed for Sb 2 S 3 /glass and Sb 2 S 3 /PEI 7.2 10 -3 nm -2 and 0.2 where I (hkl) is the measured intensity for (hkl) 10 -3 nm -2 , respectively. We can assume that the diffracting plan, I 0(hkl) is the corresponding films has the larger crystallite size has the lower intensity for randomly oriented sample taken structural defects. from the JCPDS card and N is the number of Figure 3 displays 3D AFM images (10 μm× 10 observed diffraction peaks. The variation of the μm) of Sb 2 S 3 /glass and Sb 2 S 3 /PEI thin films, texture coefficient of all Sb 2 S 3 thin films is along with the contact angle images. shown in insert Figure 1. The change in The average RMS roughnesses are found to be crystallite preferred orientation for (a) and (b) 33 nm and 116 nm for Sb 2 S 3 /glass and thin films can be explained by the difference Sb 2 S 3 /PEI, respectively. It is observed that using between the morphology of substrate surface. PEI substrate causes higher roughness than the Notably, the contact angle measurements of PEI glass substrate. Indeed, the surface of the and glass substrate show that the PEI substrate polymer is more irregular than the glass surface (Ө =76°) is more hydrophobic than the glass one causing, as a consequence, the different observed (Ө =50°) (figure 2). The variation of the morphologies of Sb 2 S 3 thin films. We can hydrophobicity is due to the difference in assume that the structural variations such as the adhesion forces (Van Der Wall's forces) between texture and microstructural parameters reveal a water and the solid surfaces. Indeed, it is noted significant variation in the morphology of thin that the PEI substrate has the lowest adhesion films. The variation in the morphology causes a work with higher adhesion force (118,8 10 − 3 variation on contact angle measurement of Sb 2 S 3 N/m) compared to glass one (96, 3 10 − 3 N/m), thin films. The static contact angles of which is related to the difference in both Sb 2 S 3 /glass and Sb 2 S 3 /PEI films are found to be composition and morphology of substrate 66 ° and 162° respectively. As it is known the surfaces. The polymer PEI substrate inherently surface roughness is assumed to be among has a low surface energy, namely, a hydrophobic principal a factor which impinges surface character that results in poor adhesion. wettability [6], which is in agreement with AFM Consequently, the grown samples show different observations. We can note that the Sb 2 S 3 /glass preferential orientations due to the surface has a hydrophilic surface however the Sb 2 S 3 /PEI energy of the substrate [5]. has a superhydrophobic one. This The substrate nature affects also the superhydrophobic character of Sb 2 S 3 /PEI surface microstructural parameters of Sb 2 S 3 thin films thin films makes this material good candidate for such as the crystallite size and structural defects. self-cleaning surface devices. Using Debye Scherrer’s formula, the crystalli te 3,0 (b) (111) (112) 2,5 (402) (014) 2,0 (205) (020) (600) (111) TC 1,5 (112) 1,0 0,5 0,0 (205) (020) (600) (014) (402) Intensity (u.a) 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 (400) 3,0 (a) (200) (400) 2,5 2,0 (200) TC 1,5 1,0 0,5 0,0 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 2  Figure 1.XRD patterns:Sb 2 S 3 /PEI (a) and Sb 2 S 3 /glass (b) Figure 3. 3D AFM images and contact angle measurements of Sb 2 S 3 /PEI (a) and Sb 2 S 3 /glass (b) Figure 2. Contact angle measurements of PEI and glass substrate