Linear chemically sensitive electron tomography using DualEELS and compressed sensing

No abstract available

Morphology and local electrical properties of PTB7:PC<inf>71</inf>BM blends

© 2015 The Royal Society of Chemistry. The power conversion efficiency of single layer organic solar cells can approach 10% with blends such as the polymer PTB7 and the fullerene derivative PC71BM. Here the detailed structure of PTB7:PC71BM blends deposited with and without addition of diiodooctane is studied by transmission electron microscopy and scanning probe microscopy. The details of bulk structure, such as the thickness of the layer covering fullerene domains and the grain structure of the film are examined. We find that fullerene-rich domains can be near the surface of the film or buried deeper, near the substrate. The local electrical properties of these blends are studied by conductive atomic force microscopy for different configurations of electrodes. Different power conversion efficiencies of blends with and without diiodooctane are explained in terms of local photoconductive properties

Morphology and local electrical properties of PTB7:PC<inf>71</inf>BM blends

© 2015 The Royal Society of Chemistry. The power conversion efficiency of single layer organic solar cells can approach 10% with blends such as the polymer PTB7 and the fullerene derivative PC71BM. Here the detailed structure of PTB7:PC71BM blends deposited with and without addition of diiodooctane is studied by transmission electron microscopy and scanning probe microscopy. The details of bulk structure, such as the thickness of the layer covering fullerene domains and the grain structure of the film are examined. We find that fullerene-rich domains can be near the surface of the film or buried deeper, near the substrate. The local electrical properties of these blends are studied by conductive atomic force microscopy for different configurations of electrodes. Different power conversion efficiencies of blends with and without diiodooctane are explained in terms of local photoconductive properties

Morphology and local electrical properties of PTB7:PC<inf>71</inf>BM blends

© 2015 The Royal Society of Chemistry. The power conversion efficiency of single layer organic solar cells can approach 10% with blends such as the polymer PTB7 and the fullerene derivative PC71BM. Here the detailed structure of PTB7:PC71BM blends deposited with and without addition of diiodooctane is studied by transmission electron microscopy and scanning probe microscopy. The details of bulk structure, such as the thickness of the layer covering fullerene domains and the grain structure of the film are examined. We find that fullerene-rich domains can be near the surface of the film or buried deeper, near the substrate. The local electrical properties of these blends are studied by conductive atomic force microscopy for different configurations of electrodes. Different power conversion efficiencies of blends with and without diiodooctane are explained in terms of local photoconductive properties

Electron Tomography of Polymer Solar Cells Using Compressed Sensing

Recently, the single layer polymer solar cell (PSC) based on bulk heterojunction (BHJ) blend of two materials: fullerene derivative [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) and a polymer with alternating units of thieno{3,4–b} thiophene and benzodithiophene (PTB7) has received significant attention [1], since high power conversion efficiency (PCE) of 9.2% has been reported for devices based on this mixture [2]. Unfortunately, little is known about the nanoscale organisation of PTB7:PC71BM blends beyond some 2D imaging. In this work, we extends our previous study in [8] electron tomography (ET) [3] and a new ET image reconstruction method, DLET, to investigate the 3D organisation of such blends using. ET plays an essential role in the study of 3 dimensional (3D) nanostructures. It involves reconstructing 3D objects from a series of 2D images by sequential tilting of the sample about a single axis. This technique, although originally designed for use in the life sciences, has also been applied to the study of polymer blends using bright-Field TEM (BFTEM) as in [4]. We used energy filtered electron tomography [5] using thin cross-sections through the blend cut using a FIB (Nova Nanolab, FEI). Three-dimensional reconstruction was performed using a new compressed sensing based algorithm, DLET [6,7], which enables high-fidelity, low-noise reconstruction from relatively few projections and minimizes artifacts from the missing wedge in the tilt data. The result from DLET is also compared with traditional methods such as Weighted back projection (WBP) and simultaneous iterative reconstructive technique (SIRT). The volume rendering visualisations of the reconstructions are shown in Figure (1). EFTEM results clearly show that domains in the blend are PC71BM-rich (i.e. contain more carbon as in Fig.1(b)). The EFTEM tomography clearly reveals that these ellipsoids and are not spherical. TEM and SEM measurements of device cross-section show existence of thin skin layer covering domains

Linear chemically sensitive electron tomography using DualEELS and compressed sensing

No abstract available

Combined ultramicrotomy and atomic force microscopy study of the structure of a bulk heterojunction in polymer solar cells

Originally published in Russion, in Fizika i Tekhnika PoluprovodnikovВ данной работе описан и применен способ визуализации внутренней структуры фотоактивных слоев полимерных солнечных батарей методами сканирующей зондовой микроскопии, основанный на использовании ультрамикротома для получения срезов фотоактивного слоя . Данный метод позволяет использовать преимущества атомно - силовой микроскопии при изучении стру ктуры в объеме мягких образцов, такие как вы сокий контраст изображений и способность измерять различные свойства поверхности с нанометровым разрешением. Описанным методом и сследованы образцы фотоактивного слоя полимерной солнечной батареи на основе смеси производной тиофена PTB 7 и производной фуллер ена PC 71 BM . Обнаруж ены новые детали вн утренней структуры данной смеси, позволяющие сделать дополнительные выводы о механизме влияния добавок дий одооктана на эффективность солнечных элементов. A method for visualization via atomic-force microscopy of the internal structure of photoactive layers of polymer solar cells using an ultramicrotome for photoactive layer cutting is proposed and applied. The method creates an opportunity to take advantage of atomic-force microscopy in structural investigations of the bulk of soft samples. Such advantages of atomic-force microscopy include a high contrast and the ability to measure various surface properties at nanometer resolution. Using the proposed method, samples of the photoactive layer of polymer solar cells based on a mixture of PTB7 polythiophene and PC71BM fullerene derivatives are studied. The disclosed details of the bulk structure of this mixture allow us to draw additional conclusions about the effect of morphology on the efficiency of organic solar cells.PostprintPeer reviewe

Six-year multicenter study on short-term peripheral venous catheters-related bloodstream infection rates in 246 intensive units of 83 hospitals in 52 cities of 14 countries of Middle East: Bahrain, Egypt, Iran, Jordan, Kingdom of Saudi Arabia, Kuwait, Lebanon, Morocco, Pakistan, Palestine, Sudan, Tunisia, Turkey, and United Arab Emirates—International Nosocomial Infection Control Consortium (INICC) findings

Short-term peripheral venous catheters-related bloodstream infections (PVCR-BSIs) rates have not been systematically studied, and data on their incidence by number of device-days is not available. Prospective, surveillance study on PVCR-BSI conducted from September 1st, 2013 to 31st Mays, 2019 in 246 intensive care units (ICUs), members of the International Nosocomial Infection Control Consortium (INICC), from 83 hospitals in 52 cities of 14 countries in the Middle East (Bahrain, Egypt, Iran, Jordan, Kingdom of Saudi Arabia, Kuwait, Lebanon, Morocco, Pakistan, Palestine, Sudan, Tunisia, Turkey, and United Arab Emirates). We applied U.S. We followed 31,083 ICU patients for 189,834 bed-days and 202,375 short term peripheral venous catheter (PVC)-days. We identified 470 PVCR-BSIs, amounting to a rate of 2.32/1000 PVC-days. Mortality in patients with PVC but without PVCR-BSI was 10.38%, and 29.36% in patients with PVC and PVCR-BSI. The mean length of stay in patients with PVC but without PVCR-BSI was 5.94 days, and 16.84 days in patients with PVC and PVCR-BSI. The microorganism profile showed 55.2 % of gram-positive bacteria, with Coagulase-negative Staphylococci (31%) and Staphylococcus aureus (14%) being the predominant ones. Gram-negative bacteria accounted for 39% of cases, and included: Escherichia coli (7%), Klebsiella pneumoniae (8%), Pseudomonas aeruginosa (5%), Enterobacter spp. (3%), and others (29.9%), such as Serratia marcescens. PVCR-BSI rates found in our ICUs were much higher than rates published from USA, Australia, and Italy. Infection prevention programs must be implemented to reduce the incidence of PVCR-BSIs