One-step Preparation of ZnO Electron Transport Layers Functionalized with Benzoic Acid Derivatives

We present a "one-step" approach to modify ZnO electron transport layers (ETLs) used in organic solar cells. This approach involves adding benzoic acid (BZA) derivatives directly to the ZnO precursor solution, which are then present at the surface of the resulting ZnO film. We demonstrate this approach for three different BZA derivatives, namely benzoic acid, chlorobenzoic acid, and 4-hydrazinobenzoic acid. For all molecules, improved device performance and stability is demonstrated in solar cells using an active layer blend of PTQ10 (donor) and ITIC-Br (non-fullerene acceptor) compared to such cells prepared using untreated ZnO. Furthermore, similar or improved device performance and stability is demonstrated compared to conventional PEIE treatment of ZnO. The presence of the BZA derivatives at the surface after processing is established using X-ray photoelectron spectroscopy and near-edge X-ray absorption fine-structure spectroscopy. From atomic force microscopy analysis and X-ray diffraction studies, the addition of BZA derivatives appears to restrict ZnO grain growth; however, this does not negatively impact device performance. ZnO layers treated with BZA derivatives also exhibit higher water contact angle and lower work function compared to untreated ZnO. This approach enables simplification of device manufacture while still allowing optimization of the surface properties of metal oxide ETLs. Keywords: electron transport layers, zinc oxide, organic solar cells, surface modificationComment: Manuscript: 25 pages, 8 figures, 5 tables. Supplementary Material: 36 pages, 22 figures, 13 tables. Submitted to Solar Energy Materials and Solar Cell

Printing and Coating Techniques for Scalable Organic Photovoltaic Fabrication

Within recent years, there has been an increased interest towards organic photovoltaics (OPVs), especially with their significant device performance reaching beyond 19% since 2022. With these advances in the device performance of laboratory-scaled OPVs, there has also been more attention directed towards using printing and coating methods that are compatible with large-scale fabrication. Though large-area (>100 cm2) OPVs have reached an efficiency of 15%, this is still behind that of laboratory-scale OPVs. There also needs to be more focus on determining strategies for improving the lifetime of OPVs that are suitable for scalable manufacturing, as well as methods for reducing material and manufacturing costs. In this paper, we compare several printing and coating methods that are employed to fabricate OPVs, with the main focus towards the deposition of the active layer. This includes a comparison of performances at laboratory (2), small (1–10 cm2), medium (10–100 cm2), and large (>100 cm2) active area fabrications, encompassing devices that use scalable printing and coating methods for only the active layer, as well as “fully printed/coated” devices. The article also compares the research focus of each of the printing and coating techniques and predicts the general direction that scalable and large-scale OPVs will head towards

Polyolefin composition for medium/high/extra high voltage cables comprising benzil-type voltage stabiliser

The present invention relates to a polyolefin composition comprising (A) a polyolefin, (B) a benzil derivative comprising, preferably consisting of, the structural unit according to the following formula (I) wherein R1, R2, R3, R4, R5, R6, R7, R8, R9 and R10 independently from each other are hydrogen, or a hydrocarbyl group which may contain heteroatoms or at least two of said R1, R2, R3, R4, R5, R6, R7, R8, R9 and R10 together with the ring atoms of the ring system of formula (I) they are attached to, form a further aromatic or non-aromatic ring fused to the ring system of formula (I) and at least R1 or R2 is an ester group. The invention also relates to a wire or cable, in particular a medium, high or extra high voltage cable, comprising such a composition, and to the use of such a composition for the production of a wire or cable, in particular a medium, high or extra high voltage cable

Thioxanthone Derivatives as Stabilizers Against Electrical Breakdown in Cross-Linked Polyethylene for High Voltage Cable Applications

In the search of voltage stabilizers for high voltage underground cables the chemical synthesis and electrical tree inhibiting effect of a series of thioxanthone derivatives in cross-linked low-density polyethylene (XLPE) is reported. The strongest increase in electrical tree initiation field under high-voltage alternating current (HVAC) conditions was 55% compared to reference XLPE after the addition of 0.3 wt% 9-oxo-9H-thioxanthen-2-yl methacrylate. Thermal analysis, small angle X-ray scattering and gel content measurements showed that the addition of the stabilizers did not significantly influence the microstructure and gel fraction of XLPE. A comparison between the stabilizing effects of the thioxanthone derivatives and previously reported photophysical properties revealed that a short lifetime of the triplet excited state can be related to a good voltage-stabilizing effect

Tailored Side-Chain Architecture of Benzil Voltage Stabilizers for Enhanced Dielectric Strength of Cross-Linked Polyethylene

The synthesis and physico-chemical properties of seven benzil-type voltage stabilizers are reported. The benzil core is substituted with alkyl chains of different length that are linked to the benzil core via an ester, ether, or tertiary amine group. All additives can be melt-processed with low-density polyethylene (LDPE). Fourier-transform infrared spectroscopy confirms that benzil compounds are not affected by the LDPE cross-linking reaction induced by dicumyl peroxide. Moreover, a combination of gel content measurements, thermal analysis, and small-angle X-ray scattering indicates that the presence of benzil voltage stabilizers does not significantly alter the microstructure of cross-linked polyethylene (XLPE). Electrical tree inhibition experiments under high-voltage alternating current conditions show that all investigated additives substantially enhance the dielectric strength of the insulating material at a concentration of only 10 mmol kg−1. The highest improvement in dielectric strength, of more than 70% with respect to reference XLPE, is obtained with voltage stabilizers, which carry short (methyl) side chains that are linked to the benzil core via an ester or tertiary amine group

Purification of used scintillation liquids containing the alpha emitters americium and plutonium

In Sweden, alpha radioactive waste liquids with an activity over some kBq per waste container cannot be sent for final storage. Therefore, in this work, a method for a purification of alpha active scintillation cocktails was developed. Until today (March, 2013) more than 20 L of scintillation liquids have successfully been purified from americium and plutonium. The products of the process are a solid fraction that can be sent to final storage and a practically non-radioactive liquid fraction that can be sent to municipal incineration

Optimization of the power conversion efficiency in high bandgap pyridopyridinedithiophene-based conjugated polymers for organic photovoltaics by the random terpolymer approach

We report that the organic photovoltaic (OPV) performance of wide band gap pyridopyridinedithiophene-based conjugated polymers can be significantly improved by employing the random terpolymer approach for the development of new pyridopyridinedithiophene-based conjugated polymers. This is demonstrated by the synthesis of the alternating copolymer (P1) consisting of 3,3′-difluoro-2,2′-bithiophene and pyridopyridinedithiophene and the random terpolymer (P2) containing pyridopyridinedithiophene 3,3′-difluoro-2,2′-bithiophene and thiophene. OPV devices fabricated by P1 and P2 in combination with PC61BM and PC71BM in an inverted device configuration exhibited power conversion efficiencies (PCEs) of 1.5% and 4.0%, respectively. We identified that the main reason for the enhanced performance of the OPV devices based on the P2 random copolymer was the improved morphology (miscibility) between P2 and PCBM as compared to P1. More specifically, atomic force microscopy (AFM) and scanning electron microscopy (SEM) studies revealed that the P1 based films showed rougher surface with clear crystallization/precipitation of the polymer chains even after the addition of chloronaphthalene (CN) to the chloroform processing solvent which significantly limited the short circuit current density (JSC), fill factor (FF) and overall performance of the prepared photovoltaic devices. On the other hand, P2 based films showed better miscibility with the acceptor particularly when processed using 5% CN containing chloroform solvent giving a respectable improvement in the PCE of the photovoltaic devices

A New Application Area for Fullerenes: Voltage Stabilizers for Power Cable Insulation

Fullerenes are shown to be efficient voltage-stabilizers for polyethylene, i.e., additives that increase the dielectric strength of the insulation material. Such compounds are highly sought-after because their use in power-cable insulation may considerably enhance the transmission efficiency of tomorrow\u27s power grids. On a molal basis, fullerenes are the most efficient voltage stabilizers reported to date