Rheological and physical characterization of PEDOT: PSS/graphene oxide nanocomposites for perovskite solar cells

In this work, the influence of graphene oxide (GO) doped Poly(3,4 ethylenedioxythiophene):poly (styrenesulfonate)(PEDOT:PSS) thin nanocomposite on an indium–tin-oxide (ITO) anode, as hole transport layer (HTL) in perovskite solar cells, was investigated. Different concentrations of GO were added into the PEDOT:PSS in order to enhance its conductivity. In particular, the influence of GO content on the rheological and thermal properties of Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/GO nanocomposites was initially examined. The GO filler was prepared by using modified Hummers method and dispersed into PEDOT:PSS in different quantity (ranging from 0.05 to 0.25 %wt/wt). The obtained nanocomposite solutions were analyzed by rheological characterizations in order to evaluate the influence of the GO filler on the viscosity of the PEDOT:PSS matrix. The wettability of solutions was evaluated by Contact Angle (CA) measurements. The quality of GO dispersion into the polymer matrix was studied using Scanning electron microscopy (SEM) and X-ray diffraction (XRD). Thermal characterizations (DSC and TGA) were, finally, applied on nanocomposite films in order to evaluate thermal stability of the films as well as to indirectly comprehend the GO influence on PEDOT:PSS-water links

3D to 2D reorganization of silver–thiol nanostructures, triggered by solvent vapor annealing

Metal–organic composites are of great interest for a wide range of applications. The control of their struc-ture remains a challenge, one of the problems being a complex interplay of covalent and supramolecularinteractions. This paper describes the self-assembly, thermal stability and phase transitions of orderedstructures of silver atoms and thiol molecules spanning from the molecular to the mesoscopic scale.Building blocks of molecularly defined clusters formed from 44 silver atoms, each particle coated by amonolayer of 30 thiol ligands, are used as ideal building blocks. By changing solvent and temperature it ispossible to tune the self-assembled 3D crystals of pristine nanoparticles or, conversely, 2D layered structures, with alternated stacks of Ag atoms and thiol monolayers. The study investigates morphological,chemical and structural stability of these materials between 25 and 300 °Cin situandex situat the nano-scale by combining optical and electronic spectroscopic and scattering techniques, scanning probemicroscopies and density-functional theory (DFT) calculations. The proposed wet-chemistry approach isrelatively cheap, easy to implement, and scalable, allowing the fabricated materials with tuned propertiesusing the same building blocks

Preparazione e caratterizzazione di espansi in PVC per la produzione di pannelli compositi utilizzati in campo eolico e navale

I materiali polimerici espansi sono utilizzati come core di pannelli compositi di tipo sandwich (tipicamente a base di polivinilcloruro, polistirene e poliuretani). Negli ultimi anni molte ricerche si sono concentrate sulla possibilità di aumentare le loro proprietà meccaniche, termiche, di resistenza agli agenti esterni, ignifughe, etc cercando contemporaneamente la diminuzione del peso e del costo (sia delle materia prime che di processo). In questo contesto, l’obiettivo di questa tesi di laurea è lo studio, la preparazione e la caratterizzazione di espansi in PVC di natura cross-linked per la produzione di pannelli compositi a sandwich potenzialmente utilizzabili in campo eolico e navale

Bulk Heterojunction Solar Cells: The Role of Alkyl Side Chain on Nanoscale Morphology of Sulfur Over-rich Regioregular Polythiophene/Fullerene Blends

R e g i o r e g u l a r HH-TT p o l y ( 3 , 3 ′ - thioalkylbithiophene)s-bearing branched or linear alkyl sidechain substituents (PT2SR) have been synthesized and characterized to investigate their behavior, when used as electron-donor components in blend with a fullerene derivative [[6,6]-phenyl-C61-butyric acid methyl ester (PCBM)] as an electron acceptor, in air-processed photovoltaic solar cells with bulk heterojunction architecture. The optoelectronic characteristics, energy gap, nanoscale morphology, and crystallinity of the blends (PT2SR/PCBM) were examined by ultraviolet− visible spectroscopy, cyclic voltammetry, Kelvin probe force microscopy (KPFM), and X-ray diffraction (XRD). We demonstrate that thioalkyl substituents are able to influence the PCBM self-assembly and the morphology of the polymeric film, important parameters to maximize the efficiency of the solar cell. In particular, the presence of chemical branching in the side chain of the sulfur over-rich polythiophene backbone favors the formation of PCBM clusters, of size of about 100 ± 30 nm, as confirmed by XRD and KPFM measurements. This facilitates the intermixing between donor and acceptor materials at the nanoscale level, determining an increase in the device performance

Bulk Heterojunction Solar Cells: The Role of Alkyl Side Chain on Nanoscale Morphology of Sulfur Over-rich Regioregular Polythiophene/Fullerene Blends

Regioregular HH-TT poly­(3,3′-thioalkylbithiophene)­s-bearing branched or linear alkyl side-chain substituents (PT2SR) have been synthesized and characterized to investigate their behavior, when used as electron-donor components in blend with a fullerene derivative [[6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM)] as an electron acceptor, in air-processed photovoltaic solar cells with bulk heterojunction architecture. The optoelectronic characteristics, energy gap, nanoscale morphology, and crystallinity of the blends (PT2SR/PCBM) were examined by ultraviolet–visible spectroscopy, cyclic voltammetry, Kelvin probe force microscopy (KPFM), and X-ray diffraction (XRD). We demonstrate that thioalkyl substituents are able to influence the PCBM self-assembly and the morphology of the polymeric film, important parameters to maximize the efficiency of the solar cell. In particular, the presence of chemical branching in the side chain of the sulfur over-rich polythiophene backbone favors the formation of PCBM clusters, of size of about 100 ± 30 nm, as confirmed by XRD and KPFM measurements. This facilitates the intermixing between donor and acceptor materials at the nanoscale level, determining an increase in the device performance