Optical, morphological and photocatalytic properties of biobased tractable films of chitosan/donor-acceptor polymer blends

Biobased tractable films consisting of blends of chitosan (CS) with polymer bearing carbazole derivatives as pendant groups and fluorene-thiophene as donor-acceptor units (referred to as DA) were prepared, and their optical, morphological and photocatalytic properties were studied. DA was dissolved in tetrahydrofuran (THF) and mixed with an acidified aqueous solution containing chitosan to obtain chitosan/DA (CS/DA) films by solution casting. The fabricated biobased films were characterized using spectroscopic techniques (FT-IR and UV–vis), thermogravimetry, mechanical assays, contact angle analysis, and atomic force microscopy (AFM). The effects of varying DA compositions and the results of exposure to visible-light irradiation of the films were also analyzed. The results indicated the existence of interactions between chitosan and DA and a potentially profitable light-driven response of these biobased films. This behavior was reflected in the optical, topographical, and contact angle properties of the films, which exhibited different characteristics before and after visible-light exposure. Finally, the photocatalytic performance of the biobased films was tested via the decomposition of methyl orange (MO), as a reaction model system. Our results revealed a significant photocatalytic activity (according to biobased film composition, approximately 64 % and 87 % of methyl orange were degraded under continuous visible-light irradiation for 120 min) of the films which is attributed to the combined presence and synergetic effects of the film-forming ability of chitosan and the photoproperties of DA

Carbazole based electrochromic polymers with benzoazole units: Effect of heteroatom variation on electrochromic performance

A series of carbazole-based polymers were synthesized via Suzuki polymerization between N-(2-ethylhexyl)carbazole-3,6-bis(ethyleneboronate) (Cbz) and dibromobenzazole unit. Three different polymers, PCBN, PCBS and PCBSe were obtained from 4,7-dibromo-2-hexyl-2H-benzotriazole (BN), 4,7-dibromo-2,1,3-benzothiadiazole- (BS) and 4,7-dibromo-2,1,3-benzoselenadiazole (BSe), respectively. It is observed that, the variation of heteroatoms (N,S and Se) on the benzazole unit have most important effect on electro-optic properties of the PCBX polymers. Neutral state color of the polymer films and their electrochromic performances are also influenced. Among the synthesized polymers, the PCBS bearing 2,1,3-benzothiadiazole as acceptor units has a broad absorption and 50% of ΔT in the near-IR regime at the oxidized state. This property of PCBS is a great advantage for near-IR electrochromic applications

Solution processable neutral state colourless electrochromic devices: effect of the layer thickness on the electrochromic performance

WOS: 000387229000023In this study, a neutral state colourless electrochromic device fabricated through a solution process is introduced. The device contains indium doped transparent oxide coated glass as the transparent conductive electrode, poly(N-(2-ethylhexyl) carbazol-3,6-diyl) (PCbz) as the anodically colouring material, poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) as the ion storage layer and a lithium perchlorate based conducting gel electrolyte. A maximum optical contrast (Delta T%) of 58% at 800 nm is achieved by optimizing the film thickness of both the organic layers. The device that has layers of 220 nm PCbz and 120 nm PEDOT: PSS thickness revealed a high coloration efficiency (1246 cm(2) C-1) and colouring and bleaching response times of 5.6 s and 2.3 s, respectively.Canakkale Onsekiz Mart University Research Funds OfficeCanakkale Onsekiz Mart University [COMU-BAP 2015/513]S. Koyuncu is grateful to Canakkale Onsekiz Mart University Research Funds Office (Project #: COMU-BAP 2015/513) for financial support

A novel interface layer for inverted perovskite solar cells fabricated in ambient air under high humidity conditions

A novel benzotriazol based small molecule (2-hexyl-4,7-bis(5'-hexyl-2,2'-bithien-5-yl)-2H-1,2,3-benzotriazole) "BTBT" was synthesized by Suzuki coupling reaction and was successfully employed in planar inverted perovskite solar cells with ITO/BTBT/PEDOT:PSS/CH3NH3PbI3-xCl(x)/PCBM/Al configuration. Fabrication processes, including the spin coating of the perovskite layer, were performed in ambient air, under high humidity conditions (>60%). BTBT/PEDOT:PSS bilayer notably improved the power conversion efficiencies (PCE) from 9.65% to 11.6%, which corresponds to an increase of 20%