Faculty Profiles - PANDEY Shyam sudhir

Papers - PANDEY Shyam sudhir

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PCPDTBT copolymer based high performance organic phototransistors utilizing improved chain alignment Reviewed International journal

Nidhi Yadav, Nikita Kumari, Yoshito Ando, Shyam S Pandey, Vipul Singh

Optical Materials ( Elsevier ) 113 110886(1) - 110886(9) 2021.03

Language：English Publishing type：Research paper (scientific journal)

In this article, we report single component thin film based organic phototransistors (OPTs) developed using the novel ribbon-floating film transfer method (ribbon-FTM). A low band-gap copolymer, poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) has been employed to develop the photoactive thin films of the devices. The fabricated polymer films were highly anisotropic in nature. To investigate the effect of film anisotropy on the device performance, organic field effect transistors (OFETs) were fabricated in two configurations namely, parallel and perpendicular, wherein the polymeric chains were oriented in line and orthogonal to the transistor channel direction, respectively. Notable differences in charge carrier mobility and device on-off ratios were observed among the two sets of devices. An on-off ratio of 4.1 × 103 and an average mobility of 0.001 cm2/V were observed in case of the perpendicular oriented OFETs which were increased to 105 and 0.003 cm2/V for the parallel oriented OFETs. A probe into the contact resistance at the respective metal/polymer interfaces of the devices was carried out using the modified transmission line method (MTLM). 4 times lower contact resistance was observed in the parallel OFET which was anticipated to be responsible for its superior performance. Further, the fabricated devices were illuminated with monochromatic red light (Pin = 0.4 mW/cm2) to observe their performance as phototransistors. Appreciable values of photosensitivity (2 × 104) and photoresponsivity (17.6 A/W) were obtained for the parallel OPTs which were found to be much higher than those of the previously reported thin film based OPTs employing other materials fabricated through conventional film coating techniques. The results presented in this report are of key significance towards the development of highly sensitive and cost-effective phototransistors which can be used in opto-sensing and imaging applications.

DOI： 10.1016/j.optmat.2021.110886

Other Link： https://www.sciencedirect.com/science/article/pii/S0925346721000872

Investigation of Orientation in the Thin Films of Conjngated Polymer and NIR Dye Blends Fabricated by Friction Transfer Method Reviewed International journal

Kurokawa Y., Nagamatsu S., Pandey S.S.

Proceedings of AM-FPD 2021 - 28th International Workshop on Active-Matrix Flatpanel Displays and Devices: TFT Technologies and FPD Materials 96 - 99 2021.01

Unravelling the bottleneck of phosphonic acid anchoring groups aiming toward enhancing the stability and efficiency of mesoscopic solar cells Reviewed International journal

Vats A.K., Roy P., Tang L., Hayase S., Pandey S.S.

Frontiers of Chemical Science and Engineering 16 ( 7 ) 1060 - 1078 2021.01

Solvent-Assisted Friction Transfer Method for Fabricating Large-Area Thin Films of Semiconducting Polymers with Edge-On Oriented Extended Backbones Reviewed

Kumari N., Pandey M., Syafutra H., Nagamatsu S., Nakamura M., Pandey S.S.

ACS Applied Materials and Interfaces 12 ( 49 ) 55033 - 55043 2020.12

Language：English Publishing type：Research paper (scientific journal)

© Recent past has witnessed huge scientific efforts aiming toward enhancing in-plane charge transport by unidirectional orientation of conjugated polymer (CP) backbones adopting various techniques. However, in most of the existing methods, excess amounts of toxic halogenated solvents and preaggregation in solution are inevitable, which are the main bottlenecks toward large-scale fabrication. Solvent-assisted friction transfer (SAFT) is being reported as a novel method and improvisation over conventional friction transfer to expand its versatility. In this method, application of a small amount of the solvent (∼3 μL) during drawing not only leads to the entirely changed film morphology and molecular orientation but also addresses the existing substrate compatibility issues. Utilizing poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]-thiophene] as a representative CP under SAFT technique, films with extended backbone and edge-on orientation was successfully fabricated, which was confirmed by various characterization tools such as X-ray diffraction, polarized absorption, and polarized Raman spectroscopies. Further, anisotropic charge transport in these films was investigated by fabricating organic field-effect transistors and the role of contact resistance was also studied. Slight solvent use, compatibility with various substrates, and film fabrication with controlled orientation, and after validation of its generality on different CPs, SAFT can be expected to open new avenues in the area of printed electronics.

DOI： 10.1021/acsami.0c14874

Scopus

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Comprehensive performance analysis of dye-sensitized solar cells using single layer TiO<inf>2</inf> photoanode deposited using screen printing technique Reviewed

Khalifa A., Shafie S., Hasan W.Z.W., Lim H.N., Rusop M., Pandey S.S., Vats A.K., AlSultan H.A., Samaila B.

Optik 223 2020.12

Language：English Publishing type：Research paper (scientific journal)

© 2020 Elsevier GmbH A single-layer N719 sensitized nanocrystalline TiO2 films have been successfully deposited on FTO-coated glass substrates using the screen-printing technique with four different thicknesses (10, 12, 14 and 18 μm) and used as simple and low cost photoanodes for dye-sensitized solar cells (DSSCs). The thickness was controlled by adjusting the distance between the screen-printing mesh and the FTO-coated substrate using the two height control bolts. The films were deposited using one-time screen-printing method. So that the multiple screen-printing and annealing cycles can be reduced. Furthermore, the cell fabrication time was reduced as well as the problem of recombination at the interfacial layers between the TiO2 films was avoided. The thickness of the TiO2 films was measured by the surface profilometer. The prepared photoanode samples were characterized using FESEM, EDX, AFM, and UV–vis-NIR spectroscopies. The ruthenium dye soaking time was optimized at 48 h. The photovoltaic parameters such as short circuit current density (Isc), open-circuit voltage (Voc), fill factor (FF) and power conversion efficiency (η) were measured for fabricated cells at room temperature under one sunlight 100 mW/cm2 illumination using the solar simulator. The effect of TiO2 film thickness on the fabricated DSSCs performance parameters was studied. DSSC devices with average thickness 12μm achieved the highest conversion efficiency of 5.13 % with Jsc = 12.12 mA/cm2, and Voc = 0.69 V. The obtained results revealed that the amount of the adsorbed dye increases with the increase in the TiO2 film thickness and thus improve photogenerated current. However, exceeding the optimum photoanode thickness results in decline in the photogenerated current and the overall efficiency due to back electrons recombination and the lower photoanode transmittance.

DOI： 10.1016/j.ijleo.2020.165595

Scopus

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Ordered arrangement of F4TCNQ anions in three-dimensionally oriented P3HT thin films Reviewed

Nagamatsu S., Pandey S.S.

Scientific Reports 10 ( 1 ) 2020.12

Language：English Publishing type：Research paper (scientific journal)

© 2020, The Author(s). An ordered arrangement of electron-accepting molecular dopant, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), in three-dimensionally (3D) oriented poly(3-hexylthiophene) (P3HT) film was clarified. The 3D oriented P3HT thin films prepared by the friction-transfer technique were doped with F4TCNQ by dipping into an acetonitrile solution. The presence of F4TCNQ anions in the 3D oriented P3HT thin films was investigated by polarized ultraviolet/visible/near-infrared absorption spectroscopy, grazing incidence X-ray diffractometry, polarized Fourier transform infrared spectroscopy (FT-IR), and infrared p-polarized multiple-angle incidence resolution spectroscopy (pMAIRS). The F4TCNQ-doped 3D oriented P3HT films showed anisotropic properties in all characterizations. In particular, the anisotropic molecular vibrations from polarized FT-IR and pMAIRS have clearly revealed orientations of polymeric chains and molecular dopant molecules. Considering the results from several independent techniques indicated that F4TCNQ anions in the 3D oriented P3HT were orderly arranged in a 3D manner with respect to the 3D oriented P3HT such that their molecular long-axis parallel to the P3HT backbone, with in-plane molecular orientation. Additionally, the direction of the optical transition moment of the F4TCNQ anion was found to be parallel to the molecular short-axis.

DOI： 10.1038/s41598-020-77022-0

Scopus

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Effect of electrolyte for back contact transparent conducting oxide-less dye-sensitized solar cells: Iodine versus cobalt Reviewed

Molla M.Z., Baranwal A.K., Hayase S., Pandey S.S.

Journal of Photonics for Energy 10 ( 4 ) 2020.10

Language：English Publishing type：Research paper (scientific journal)

© 2020 Society of Photo-Optical Instrumentation Engineers (SPIE). Grätzel solar cells are reported in a transparent conducting oxide-less (TCO-less) back-contact dye-sensitized solar cell (BC-DSC) architecture using a stainless steel mesh-protected working electrode along with nanoporous TiO2 semiconductor and metal-free D205 dye. Liquid electrolytes play a significant role for the dye regeneration in the working operation of TCO-less BC-DSCs; therefore, we report the effectiveness of two different commonly utilized electrolytes (iodine-and cobalt-based redox shuttles) for the construction and performance of TCO-less dye-sensitized solar cells (DSCs). Differential performance of DSCs thus fabricated was interpreted utilizing impedance spectral and lifetime analysis. It was found that although utilization of cobalt bipyridyl complex-based electrolyte was able to harvest higher photons in the lower wavelength region (330 to 430 nm) as compared to its iodine electrolyte counterparts, hampered dye regeneration due to reduced driving force and slower ion diffusion in combination with higher charge transport resistance at TiO2 / dye / electrolyte was responsible for relatively hampered photovoltaic performance at peak absorption.

DOI： 10.1117/1.JPE.10.045501

Scopus

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Boosting the Efficiency of Low-Cost T-C-O-Less Dye-Sensitized Solar Cells Employing Nanoparticle Spacers and Cobalt Complex Redox Shuttle Reviewed

Molla M.Z., Baranwal A.K., Hayase S., Pandey S.S.

ACS Applied Electronic Materials 2 ( 9 ) 2721 - 2729 2020.09

Language：English Publishing type：Research paper (scientific journal)

© 2020 American Chemical Society. A strategy has been explored to enhance the diffusion of Co2+/3+ species through the dye-stained nanoparticle spacer employed as an electrolyte absorbing layer with different nanoparticle sizes of TiO2 (30 and 20 nm) and ZrO2 (15 nm) films in transparent conducting oxide-less back-contact dye-sensitized solar cells (T-C-O-less B-C-DSCs). A dye-stained nanoparticle spacer with a relatively larger particle of the TiO2 (30 nm) film brought about easy diffusion of cobalt(II/III) complexes leading to an enhanced photoconversion efficiency (PCE) of 6.55% as compared to relatively smaller nanoparticle of the TiO2 (20 nm) film (4.95%) and ZrO2 (15 nm) film (2.03%). The T-C-O-less B-C-DSC exhibits a lower PCE of 6.55% relative to the T-C-O-based DSC (9.10%) owing to relatively hampered diffusivity of [Co(bpy)3]3+/2+ complexes through perforated holes of the SS-mesh as well as the nanoparticle spacer. A differential study reveals that the cobalt electrolyte exhibits much improved light accumulation in the range 330-430 nm relative to the iodine electrolyte counterpart. The corrosion study of the SS-mesh and Ti-protected SS-mesh reveals that stable T-C-O-less B-C-DSCs can be attained only by the cobalt electrolyte because of its mild nature toward the SS-mesh and Ti metal as compared to the iodine electrolyte.

DOI： 10.1021/acsaelm.0c00437

Scopus

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Parametric optimization of back-contact T-C-O-free dye-sensitized solar cells employing indoline and porphyrin sensitizer based on cobalt redox electrolyte Reviewed

Molla M.Z., Baranwal A.K., Kapil G., Hayase S., Pandey S.S.

Solar Energy 208 411 - 418 2020.09

Language：English Publishing type：Research paper (scientific journal)

© 2020 International Solar Energy Society Transparent-conductive-oxide-free (T-C-O-free) back-contact (B-C) dye-sensitized solar cell (DSC) utilizing flexible Stainless Steel (SS) mesh (SS-mesh) supported with mesoporous TiO2 as a photoanode employing cobalt electrolyte is being presented. A thin layer of Ti metal over the SS-mesh was ascertained to be essential to retard the back electron reaction, which was confirmed by the dark current measurements. The interfacial contact between the SS-mesh and nanoporous (NP) TiO2 of the photoanode of T-C-O-free B-C-DSC was driven to influence the photovoltaic performance greatly. It was confirmed by electrochemical impedance analysis that NP TiO2 of 30 nm exhibited less charge transfer impedance observed at TiO2-dye-electrolyte interface as compared to TiO2 of having particle size of 15–20 nm. T-C-O-free B-C-DSC employing dye mixer combination of indoline dyes D-131 and D-205 (1:1) with relatively larger NP of TiO2 (30 nm) as compared to TiO2 of 15–20 nm exhibited enhanced photoconversion efficiency (PCE) of 4.02%. To increase the PCE even further, T-C-O-free B-C-DSC with cobalt based electrolyte sensitized with porphyrin (YD2-o-C8)-dye bearing a larger optical window was investigated. An optimized 10 µm thickness of the TiO2 layer was found to be optimum leading to an enhanced PCE of 5.26%.

DOI： 10.1016/j.solener.2020.08.011

Scopus

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Stability Improvement of Perovskite Solar Cells by Adding Sb-Xanthate to Precursor Solution Reviewed

Nam K.S., Krishnamurthy S., Qing S., Toyoda T., Yoshino K., Minemoto T., Ma T., Pandey S., Hayase S.

Physica Status Solidi (A) Applications and Materials Science 217 ( 18 ) 2020.09

Language：English Publishing type：Research paper (scientific journal)

© 2020 Wiley-VCH GmbH Herein, it is reported that the stability of a halogenated perovskite (PVK) solar cell consisting of an fluorine-doped tin oxide (FTO) substrate/TiO2/CH3NH3PbI3/N2,N2,N2′,N2′,N7,N7,N7′,N7′-octakis(4-methoxyphenyl)-9,9′-spirobi[9H-fluorene]-2,2′,7,7′-tetramine/Ag/Au structure is improved by adding Sb-xanthate to the PVK layer without large loss of efficiency. The Sb-element-rich layer is observed on top of the PVK layer. From the X-ray photoelectron spectroscopy (XPS) study, it is concluded that an inorganic SbxOy passivation layer on the PVK layer is prepared by baking the solution of the Sb-xanthate and the PVK precursor. The inorganic layer prevents moisture and oxygen from penetrating into the PVK layer. This article provides a new method to obtain a passivation layer on a PVK layer by baking a mixture solution in one step for improving solar cell stability.

DOI： 10.1002/pssa.202000144

Scopus

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Reduced contact resistance in organic field-effect transistors fabricated using floating film transfer method Reviewed

Bhargava K., Yadav N., Kumari N., Pandey S.S., Singh V.

Journal of Materials Science: Materials in Electronics 31 ( 18 ) 15277 - 15285 2020.09

Language：English Publishing type：Research paper (scientific journal)

© 2020, Springer Science+Business Media, LLC, part of Springer Nature. This paper presents an in-depth performance-based comparison of organic field-effect transistors (OFETs) prepared using the conventional spin coating (SC) technique and a recently developed floating film transfer method (FTM). A remarkable improvement in the performance of transistors fabricated using FTM was achieved in comparison to their SC counterparts. The estimated value of width-normalized contact resistance in FTM-based OFETs was an order lower in comparison to that of transistors prepared using SC technique. The observed results were credited to a significant enhancement in the length of π-conjugation due to the presence of edge-on oriented polymer chains of active layer deposited using FTM, leading to the lowering of carrier injection barrier at the Au/P3HT interface. These results were well supported through absorption, photoluminescence and Raman measurements as well as the anisotropy measurements using polarized absorption spectra, which also pointed towards the improvement in the polymer chain alignment of thin films prepared by FTM over that prepared by the conventional SC technique. The results indicate thin film morphology as a key towards reducing the contact resistance in OFETs.

DOI： 10.1007/s10854-020-04092-1

Scopus

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Orientation of Semiconducting Polymers via Swift Printing and Drawing Techniques for High Performance Organic Electronic Devices Reviewed

Kumari N., Sharma S., Nagamatsu S., Pandey S.S.

Proceedings of AM-FPD 2020 - 27th International Workshop on Active-Matrix Flatpanel Displays and Devices: TFT Technologies and FPD Materials 67 - 70 2020.09

Language：English Publishing type：Research paper (international conference proceedings)

© 2020 FTFMD. Recent developments in the field of organic electronics are being triggered by various approaches aiming towards enhancing the charge transport in thin-films of processable organic semiconductors such as novel molecular design, synthesis and increasing their crystallinity and molecular orientation adopting various thin film fabrication techniques. However, intriguing challenges associated with serious health and environment hazards due to inevitable use of halogenated solvents are needed to be addressed amicably before the practical realization of organic electronic devices. In order to address this issue, thin film fabrication techniques like floating-film transfer and friction transfer have been utilized to demonstrate environment friendly and sustainable fabrication of large area thin-films possessing adequate uniformity without comprising the facile charge transport. Organic field effect transistors were fabricated using different regions of the large-area thin films (≥ 10 cm2) and by optimizing casting conditions, uniformity in the field effect mobility (μ) was demonstrated. Besides this, as compared to most commonly used spin coating, one order of magnitude enhancement in the μ was successfully achieved utilizing oriented thin films fabricated by our methods.

DOI： 10.23919/AM-FPD49417.2020.9224472

Kyutacar

Scopus

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Comparative analysis of metal diffusion effects in polymer films coated with spin coating and floating film transfer techniques Reviewed

Yadav N., Bhargava K., Kumari N., Pandey S.S., Singh V.

Synthetic Metals 264 2020.06

Language：English Publishing type：Research paper (scientific journal)

© 2020 Elsevier B.V. In this work a comparative analysis between the extent of gold diffusion of the top coated gold layer into the conducting polymer matrix of spin coated polymer films and polymer films coated via floating film transfer method (FTM) has been investigated. For the sake of comparison two different device configurations i.e. ITO/rr-P3HT (spin coated)/Au and ITO/rr-P3HT (spin coated)/rr-P3HT (FTM coated)/Au have been compared. The J-V characteristics of these devices revealed a non-Ohmic injection occurring near the top gold electrode/polymer interface. Furthermore, the current flowing through the device consisting of FTM layer/Au interface was observed to be lower as compared to the one consisting of spin coated layer/Au interface, indicating higher gold diffusion in well-ordered FTM thin films. These observations have been validated by optical and structural characterization methods viz. absorption, photoluminescence, Raman spectroscopy and X-Ray Diffraction (XRD) measurement. Finally Fowler-Nordheim (FN) tunneling currents were studied under high electric field applications for the two devices which confirmed presence of higher barrier at the interface of gold and FTM coated polymer film.

DOI： 10.1016/j.synthmet.2020.116378

Scopus

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Synthesis, Photophysical characterization and dye adsorption behavior in unsymmetrical squaraine dyes with varying anchoring groups Reviewed

Ajendra Kumar Vats, Anusha Pradhan, Shuzi, Hayase, Shyam S. Pandey

Journal of Photochemistry and Photobiology A: Chemistry ( Elsevier ) 394 112467(1) - 112467(12) 2020.03

Molecular Orientation and Anisotropic Charge Transport in the Large Area Thin Films of Regioregular Poly (3-alkylthiopnes) Fabricated by Ribbon-Shaped FTM Reviewed

Atul SM Tripathi, Rakesh Kumar Gupta, Shubham Sharma, Shuichi Nagamatsu, Shyam S Pandey

Organic Electronics ( Elsevier ) 81 105683(1) - 105683(9) 2020.03

Investigation and control of charge transport anisotropy in highly oriented friction transferred polythiophene thin films Reviewed

Nikita Kumari, Manish Pandey, Shuichi Nagamatsu, Masakazu Nakamura, Shyam Sudhir Pandey

ACS Applied Materials & Interfaces ( American Chemical Society ) 12 ( 10 ) 11876 - 11883 2020.02

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

Highly oriented thin films of poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT) were prepared by friction-transfer technique followed by their characterization using polarized absorption spectroscopy, angle-dependent polarized Raman spectroscopy, and X-ray diffraction (XRD) techniques. Orientation in high-molecular-weight (MW) polymers is hampered by chain folding or entanglements, which limit their macromolecular orientation. Interestingly, utilizing high-molecular-weight PBTTT (MW > 50 kDa) and friction-transfer technique, successful fabrication of highly oriented thin films with very high dichroic ratio (∼30) was demonstrated. The role of the substrate's surface energy and its impact on the field-effect mobility (μ) of the oriented thin films were comprehensively investigated. The influence of annealing the thin films as prepared on the bare and self-assembled monolayer (SAM)-treated SiO2 surfaces exhibiting differential trends of μ was systematically investigated. This was explained by partial and complete conformational transformation of macromolecules on bare and SAM-treated SiO2 surfaces, respectively, after annealing them beyond liquid crystalline phase transition temperature, as revealed by in-plane and out-of-plane XRD results. On bare SiO2, optimum μ up to 0.03 cm2 V–1 s–1 along the backbone orientation was obtained for the thin films annealed to 120 °C; whereas, it reached up to 0.36 cm2 V–1 s–1 on SAM-treated SiO2 after annealing at 200 °C. Finally, a charge transport mechanism was proposed taking evidence from the anisotropic optical and electrical characteristics of the friction-transferred PBTTT films into consideration.

DOI： 10.1021/acsami.9b23345

Kyutacar

Other Link： https://pubs.acs.org/doi/abs/10.1021/acsami.9b23345

2D positional mapping of casting condition driven microstructural distribution in organic thin films Reviewed

Kumari N., Pandey M., Nagamatsu S., Pandey S.S.

Japanese Journal of Applied Physics 59 ( SC ) 2020.02

Language：English Publishing type：Research paper (scientific journal)

© 2019 The Japan Society of Applied Physics. Fabrication of large-area thin films and their swift characterization is highly desired for the commercial aspects of the organic electronic devices. Although a number of techniques have been proposed for the large-area thin film fabrication, the microstructural variation is still an issue. In this work, the facile characterization of distribution in thickness and macromolecular ordering in the drop-casted and spin-coated poly(3-hexylthiophene) thin films have been performed through newly developed 2D positional mapping technique. Through this technique, a comparative analysis of the absorption spectra in terms of peak absorbance and excitonic bandwidth (W) was performed for the whole sample, the lower value of W observed for the drop-casted thin film depicts its molecular ordering. Moreover, the difference in W (≈ 10 meV) was noticed between two points (≈1 mm apart) on the drop-casted film, which corresponds to the difference in microstructural ordering and it is complicated to characterize through the conventional spectroscopic techniques.

DOI： 10.7567/1347-4065/ab48b9

Scopus

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2D positional mapping of casting condition driven microstructural distribution in organic thin films Reviewed

Nikita Kumari, Manish Pandey, Shuichi Nagamatsu, Shyam S Pandey

Japanese Journal of Applied Physics ( IOP Science ) 69 ( SC ) SCCA06-1 - SCCA06-6 2019.11

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

Fabrication of large-area thin films and their swift characterization is highly desired for the commercial aspects of the organic electronic devices. Although a number of techniques have been proposed for the large-area thin film fabrication, the microstructural variation is still an issue. In this work, the facile characterization of distribution in thickness and macromolecular ordering in the drop-casted and spin-coated poly(3-hexylthiophene) thin films have been performed through newly developed 2D positional mapping technique. Through this technique, a comparative analysis of the absorption spectra in terms of peak absorbance and excitonic bandwidth (W) was performed for the whole sample, the lower value of W observed for the drop-casted thin film depicts its molecular ordering. Moreover, the difference in W (≈ 10 meV) was noticed between two points (≈1 mm apart) on the drop-casted film, which corresponds to the difference in microstructural ordering and it is complicated to characterize through the conventional spectroscopic techniques.

Kyutacar

Other Link： https://iopscience.iop.org/article/10.7567/1347-4065/ab48b9/meta

P3HT Nanofibrils Thin-Film Transistors by Adsorbing Deposition in Suspension Reviewed

Shuichi Nagamatsu, Masataka Ishida, Shougo Miyajima, Shyam S Pandey

Materials ( MDPI ) 12 ( 21 ) 3643 2019.11

Language：English Publishing type：Research paper (scientific journal)

A novel film preparation method utilizing polymer suspension, entitled adsorbing deposition in suspensions (ADS), has been proposed. The poly(3-hexylthiophene) (P3HT) toluene solution forms P3HT nanofibrils dispersed suspension by aging. P3HT nanofibrils are highly crystallized with sharp vibronic absorption spectra. By the ADS method, only P3HT nanofibrils in suspension can be deposited on the substrate surface without any disordered fraction from the dissolved P3HT in suspension. Formed ADS film contains only the nanostructured conjugated polymer. Fabricated polymer thin-film transistor (TFT) utilizing ADS P3HT film shows good TFT performances with low off current, narrow subthreshold swing and large on/off current ratio

DOI： 10.3390/ma12213643

Other Link： https://www.mdpi.com/1996-1944/12/21/3643

Clitoria ternatea flower as natural dyes for Dye-sensitized solar cells Reviewed

Azwar Hayat, A Erwin E Putra, Novriany Amaliyah, Shyam S Pandey

IOP Conference Series: Materials Science and Engineering ( IOP Science ) 619 ( 1 ) 012049-1 - 012049-6 2019.10

Language：English Publishing type：Research paper (scientific journal)

Clitoria ternatea flowers have been investigated as a natural sensitizer in Dye-sensitized solar cell (DSSC). Dried C. ternatea flowers ware immersed in ethanol for 48 hours in dark room to obtain anthocyanin pigments. We compared the photovoltaic performance of the sensitizers with Titanium dioxide (TiO2) only and TiO2 with scattering layers. C. ternatea dyes have higher Power Conversion Efficiency (PCE) when applied in TiO2 with scattering layers compared to standard TiO2 semiconductors. Scattering layer (SL) has increased the light path inside the photo-anode film that doubled the short-circuit current (Jsc) and enhanced the open circuit voltage (Voc) compared to TiO2 based cell without the SL. In conclusion, from the result, higher electron injections can be achieved by light management on photo-anode film with scattering layers as one of strategy to enhance the efficiency for further low cost and environment-friendly solar cell.

Kyutacar

Other Link： https://iopscience.iop.org/article/10.1088/1757-899X/619/1/012049/meta

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Papers - PANDEY Shyam sudhir