Creation of spin switching in graphene oxide-based hybrid film materials with an anionic Fe(III) 5Cl-salicyaldehyde-thiosemicarbazone complex.

The present article describes the synthesis of hybrid composite film materials formed during the self-assembly process through non-covalent interactions of graphene oxide (GO) nanosheets with salt 1, represented by an anionic spin-crossover complex [Fe(5Cl-thsa)] (5Cl-thsa - 5-chlorosalicylaldehyde thiosemicarbazone) and the organic tetraethylammonium cation [EtN]. The insertion of the salt 1 molecules into the interlayer space of GO nanosheets with the subsequent formation of a hybrid material GO-1 was observed. The film of the hybrid material GO-1 was characterized by scanning electron and confocal laser microscopy, EDX and XPS analysis, IR, Raman and Fe Mössbauer spectroscopy, magnetic measurements, and powder X-ray diffraction.

Mesoporous Networks of -Vinylpyrrolidone with (di)Methacrylates as Precursors of Ecological Molecular Imprinted Polymers.

Mesoporous polymer networks were prepared via the cross-linking radical copolymerization of non-toxic hydrophilic -vinylpyrrolidone (VP) with triethylene glycol dimethacrylate (TEGDM) and poly(ethylene glycol) methyl ester methacrylate (PEGMMA) in bulk, using appropriate soluble and thermodynamically compatible macromolecular additives with a branched structure as porogens. The branched copolymers of various monomer compositions were obtained by radical copolymerization in toluene, controlled by 1-decanethiol, and these materials were characterized by a wide set of physical chemical methods. The specific surface areas and surface morphology of the polymer networks were determined by nitrogen low-temperature adsorption or Rose Bengal (RB) sorption, depending on the copolymer compositions and scanning electron microscopy.

Features and Consequences of Isopropanol Burning off PTFE-rGO Aerogels.

An improved procedure for the preparation of aerogel granules of polytetrafluoroethylene-graphene oxide (PTFE-GO) with a composition of 50:50 (in wt %) and a specific density of 35 ± 2 mg/cm is described. The technique practically excludes the granule cracking. The specific density of the pellets after reduction using hydrazine vapor and annealing at 370 °C decreased to 29 ± 2 mg/cm.

Temperature Dynamics of MAPbI and PbI Photolysis: Revealing the Interplay between Light and Heat, Two Enemies of Perovskite Photovoltaics.

Regardless of the impressive photovoltaic performances demonstrated for lead halide perovskite solar cells, their practical implementation is severely impeded by the low device stability. Complex lead halides are sensitive to both light and heat, which are unavoidable under realistic solar cell operational conditions. Suppressing these intrinsic degradation pathways requires a thorough understanding of their mechanistic aspects.

Partial Substitution of Pb in CsPbI as an Efficient Strategy To Design Fairly Stable All-Inorganic Perovskite Formulations.

All-inorganic lead halide perovskites, for example, CsPbI, are becoming more attractive for applications as light absorbers in perovskite solar cells because of higher thermal and photochemical stability as compared to their hybrid analogues. However, a specific drawback of the CsPbI absorber consists of the rapid phase transition from black to yellow nonphotoactive phase at low temperatures (e.g.

Reduced Graphene Oxide Aerogel inside Melamine Sponge as an Electrocatalyst for the Oxygen Reduction Reaction.

A graphene oxide aerogel (GOA) was formed inside a melamine sponge (MS) framework. After reduction with hydrazine at 60 °C, the electrical conductive nitrogen-enriched rGOA-MS composite material with a specific density of 20.1 mg/cm was used to fabricate an electrode, which proved to be a promising electrocatalyst for the oxygen reduction reaction.

Solubilizing Side Chain Engineering: Efficient Strategy to Improve the Photovoltaic Performance of Novel Benzodithiophene-Based (X-DADAD) Conjugated Polymers.

Conjugated polymers represent a promising family of semiconductor materials for thin-film organic solar cells (OSCs). An efficient approach to improve the photovoltaic performance of conjugated polymers is engineering the side chains attached to the polymer backbone. This work reports the impact of different alkyl substituents on the optoelectronic properties, charge carrier mobilities, thin film morphology, and photovoltaic performance of novel (X-DADAD) conjugated polymers incorporating benzo[1,2-b:4,5-b']dithiophene moieties.

Efficient and Stable MAPbI-Based Perovskite Solar Cells Using Polyvinylcarbazole Passivation.

Hybrid perovskite solar cells attract a great deal of attention due to the feasibility of their low-cost production and their demonstration of impressive power conversion efficiencies (PCEs) exceeding 25%. However, the insufficient intrinsic stability of lead halides under light soaking and thermal stress impedes practical implementation of this technology. Herein, we show that the photothermal aging of a widely used perovskite light absorber such as MAPbI can be suppressed significantly by using polyvinylcarbazole (PVC) as a stabilizing agent.

Preparation and Characterization of a Flexible rGO-PTFE Film for a Supercapacitor Current Collector.

A mixture of water suspensions of graphene oxide (GO) and polytetrafluoroethylene (PTFE) was used to make the films GO-PTFE (50:50). They became conductive (2.0-2.

Light or Heat: What Is Killing Lead Halide Perovskites under Solar Cell Operation Conditions?

We report the first systematic assessment of intrinsic photothermal stability of a large panel of complex lead halides APbX incorporating different univalent cations (A = CHNH, [NHCHNH], Cs) and halogen anions (X = Br, I) using a series of analytical techniques such as UV-vis and X-ray photoelectron spectroscopy, X-ray diffraction, EDX analysis, atomic force and scanning electron microscopy, ESR spectroscopy, and mass spectrometry. We show that heat stress and light soaking induce a severe degradation of perovskite films even in the absence of oxygen and moisture. The stability of complex lead halides increases in the order MAPbBr < MAPbI < FAPbI < FAPbBr < CsPbI < CsPbBr, thus featuring all-inorganic perovskites as the most promising absorbers for stable perovskite solar cells.

Novel Superhydrophobic Aerogel on the Base of Polytetrafluoroethylene.

Polytetrafluoroethylene-based aerogel was synthesized for the first time. Graphene oxide was used as a binder. After reduction with hydrazine and annealing at 370 °C, the aerogel with a density of 29 ± 2 mg/cm became superhydrophobic.

Exploring the Photovoltaic Performance of All-Inorganic AgPbI/PbI Blends.

We present an all-inorganic photoactive material composed of AgPbI and PbI, which shows unexpectedly good photovoltaic performance in planar junction solar cells delivering external quantum efficiencies of ∼60% and light power conversion efficiencies of ∼3.9%. The revealed characteristics are among the best reported to date for metal halides with nonperovskite crystal structure.

Probing the Intrinsic Thermal and Photochemical Stability of Hybrid and Inorganic Lead Halide Perovskites.

We report a careful and systematic study of thermal and photochemical degradation of a series of complex haloplumbates APbX (X = I, Br) with hybrid organic (A = CHNH) and inorganic (A = Cs) cations under anoxic conditions (i.e., without exposure to oxygen and moisture by testing in an inert glovebox environment).

Highly Efficient All-Inorganic Planar Heterojunction Perovskite Solar Cells Produced by Thermal Coevaporation of CsI and PbI.

We report here all inorganic CsPbI planar junction perovskite solar cells fabricated by thermal coevaporation of CsI and PbI precursors. The best devices delivered power conversion efficiency (PCE) of 9.3 to 10.

Exploring the Effects of the Pb Substitution in MAPbI on the Photovoltaic Performance of the Hybrid Perovskite Solar Cells.

Here we report a systematic study of the Pb substitution in the hybrid iodoplumbate MAPbI with a series of elements affecting optoelectronic, structural, and morphological properties of the system. It has been shown that even partial replacement of lead with Cd, Zn, Fe, Ni, Co, In, Bi, Sn, and Ti results in a significant deterioration of the photovoltaic characteristics. On the contrary, Hg-containing hybrid MAPbHgI salts demonstrated a considerably improved solar cell performance at optimal mercury loading.

The chemical origin of the p-type and n-type doping effects in the hybrid methylammonium-lead iodide (MAPbI3) perovskite solar cells.

In the present Communication we discuss a field-induced and photoinduced self-doping chemistry resulting in the formation of the positively and negatively charged vacancies in the MAPbI3 perovskite films. These vacancies induce p-type and n-type doping of the perovskite absorber leading to the realization of the p-i-n device operation mechanism.

Towards understanding the behavior of indigo thin films in organic field-effect transistors: a template effect of the aliphatic hydrocarbon dielectric on the crystal structure and electrical performance of the semiconductor.

Here we report a systematic investigation of indigo thin films grown on different dielectric underlayers. It has been revealed that aliphatic hydrocarbon chains serve as templates inducing the formation of a new crystal modification of indigo which possesses advanced charge transport properties and affords a dramatic improvement in the electrical performance of organic field-effect transistors.

Material structure-composite morphology-photovoltaic performance relationship for organic bulk heterojunction solar cells.

Conjugated PPV-PPE copolymer has been investigated in organic solar cells in combination with twelve different fullerene derivatives. It was shown that the length of solubilizing alkyl chains in the fullerene derivative structures correlates well with the performance of photovoltaic cells.