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Instruments / Technical Area	Publication Details	Published
B23-Circular Dichroism	Controlling anisotropic properties by manipulating the orientation of chiral small molecules Jessica Wade , Francesco Salerno , Rachel C. Kilbride , Dong Kuk Kim , Julia A. Schmidt , Joel A. Smith , Luc M. Leblanc , Emma H. Wolpert , Adebayo A. Adeleke , Erin R. Johnston , Jenny Nelson , Tadashi Mori , Kim E. Jelfs , Sandrine Heutz , Matthew J. Fuchter Nature Chemistry 31 DOI: 10.1038/s41557-022-01044-6 Diamond Proposal Number(s): [29151] Show Abstract ▼ Abstract: Chiral π-conjugated molecules bring new functionality to technological applications and represent an exciting, rapidly expanding area of research. Their functional properties, such as the absorption and emission of circularly polarized light or the transport of spin-polarized electrons, are highly anisotropic. As a result, the orientation of chiral molecules critically determines the functionality and efficiency of chiral devices. Here we present a strategy to control the orientation of a small chiral molecule (2,2′-dicyano[6]helicene) by the use of organic and inorganic templating layers. Such templating layers can either force 2,2′-dicyano[6]helicene to adopt a face-on orientation and self-assemble into upright supramolecular columns oriented with their helical axis perpendicular to the substrate, or an edge-on orientation with parallel-lying supramolecular columns. Through such control, we show that low- and high-energy chiroptical responses can be independently ‘turned on’ or ‘turned off’. The templating methodologies described here provide a simple way to engineer orientational control and, by association, anisotropic functional properties of chiral molecular systems for a range of emerging technologies.	Oct 2022
I12-JEEP: Joint Engineering, Environmental and Processing	An operando spatially resolved study of alkaline battery discharge using a novel hyperspectral detector and X-ray tomography Thomas Connolley , Oxana V. Magdysyuk , Stefan Michalik , Phoebe K. Allan , Manuela Klaus , Paul H. Kamm , Francisco Garcia-Moreno , Jennifer A. Nelson , Matthew Veale , Matthew Wilson Journal Of Applied Crystallography 53 DOI: 10.1107/S1600576720012078 Diamond Proposal Number(s): [16771] Open Access Show Abstract ▼ Abstract: An experimental technique is described for the collection of time-resolved X-ray diffraction information from a complete commercial battery cell during discharging or charging cycles. The technique uses an 80 × 80 pixel 2D energy-discriminating detector in a pinhole camera geometry which can be used with a polychromatic X-ray source. The concept was proved in a synchrotron X-ray study of commercial alkaline Zn–MnO2 AA size cells. Importantly, no modification of the cell was required. The technique enabled spatial and temporal changes to be observed with a time resolution of 20 min (5 min of data collection with a 15 min wait between scans). Chemical changes in the cell determined from diffraction information were correlated with complementary X-ray tomography scans performed on similar cells from the same batch. The clearest results were for the spatial and temporal changes in the Zn anode. Spatially, there was a sequential transformation of Zn to ZnO in the direction from the separator towards the current collector. Temporally, it was possible to track the transformation of Zn to ZnO during the discharge and follow the corresponding changes in the cathode.	Dec 2020
I07-Surface & interface diffraction	Controlling energy levels and Fermi level en route to fully tailored energetics in organic semiconductors Ross Warren , Alberto Privitera , Pascal Kaienburg , Andreas E. Lauritzen , Oliver Thimm , Jenny Nelson , Moritz K. Riede Nature Communications 10 DOI: 10.1038/s41467-019-13563-x Diamond Proposal Number(s): [20426] Open Access Show Abstract ▼ Abstract: Simultaneous control over both the energy levels and Fermi level, a key breakthrough for inorganic electronics, has yet to be shown for organic semiconductors. Here, energy level tuning and molecular doping are combined to demonstrate controlled shifts in ionisation potential and Fermi level of an organic thin film. This is achieved by p-doping a blend of two host molecules, zinc phthalocyanine and its eight-times fluorinated derivative, with tunable energy levels based on mixing ratio. The doping efficiency is found to depend on host mixing ratio, which is explained using a statistical model that includes both shifts of the host’s ionisation potentials and, importantly, the electron affinity of the dopant. Therefore, the energy level tuning effect has a crucial impact on the molecular doping process. The practice of comparing host and dopant energy levels must consider the long-range electrostatic shifts to consistently explain the doping mechanism in organic semiconductors.	Dec 2019
I07-Surface & interface diffraction	Tuning the ambipolar behaviour of organic field effect transistors via band engineering P. R. Warren , J. F. M. Hardigree , A. E. Lauritzen , J. Nelson , M. Riede Aip Advances 9 DOI: 10.1063/1.5080505 Diamond Proposal Number(s): [18016, 20426] Open Access Show Abstract ▼ Abstract: We report on a method for fabricating balanced hole and electron transport in ambipolar organic field-effect transistors (OFETs) based on the co-evaporation of zinc-phthalocyanine (ZnPc) and its fluorinated derivative (F8ZnPc). The semiconducting behaviour of the OFET can be tuned continuously from unipolar p-type, with a hole mobility in the range of (1.7 ± 0.1) × 10−4 cm2/Vs, to unipolar n-type, with an electron mobility of (1.0 ± 0.1) × 10−4 cm2/Vs. Devices of the pristine ZnPc and F8ZnPc show a current on/off ratio of 105. By co-evaporating the p-type ZnPc with the n-type F8ZnPc, we fabricate ambipolar transistors and complementary-like voltage inverters. For the ambipolar devices, the optimum balance between the hole and electron mobilities is found for the blend of 1:1.5 weight ratio with hole and electron mobilities of (8.3 ± 0.2) × 10−7 cm2/Vs and (5.5 ± 0.1) × 10−7 cm2/Vs, respectively. Finally we demonstrate application of the ambipolar devices in a complementary-like voltage inverter circuit with the performance comparable to an inverter based on separate ZnPc and F8ZnPc OFETs.	Mar 2019
I07-Surface & interface diffraction	Quantitative analysis of the molecular dynamics of P3HT:PCBM bulk heterojunction Anne A. Y. Guilbert , Mohamed Zbiri , Alan D. F. Dunbar , Jenny Nelson The Journal Of Physical Chemistry B DOI: 10.1021/acs.jpcb.7b08312 Diamond Proposal Number(s): [15486] Show Abstract ▼ Abstract: The optoelectronic properties of blends of conjugated polymers and small molecules are likely to be affected by the molecular dynamics of the active layer components. We study the dynamics of regio-regular poly(3-hexylthiophene) (P3HT): phenyl-C61-butyric acid methyl ester (PCBM) blends using molecular dynamics (MD) simulation on time scales up to 50 ns and in a temperature range of 250-360K. First, we compare the MD results with quasi-elastic neutron scattering (QENS) measurements. Experiment and simulation give evidence of the vitrification of P3HT upon blending, and the plasticization of PCBM by P3HT. Second, we reconstruct the QENS signal based on the independent simulations of the three phases constituting the complex microstructure of such blends. Finally, we found that P3HT wrap itself around PCBM in the amorphous mixture of P3HT and PCBM; this molecular interaction between P3HT and PCBM is likely to be responsible for the observed frustration of P3HT.	Aug 2017
I07-Surface & interface diffraction	A general mechanism for controlling thin film structures in all-conjugated block copolymer:fullerene blends Rajeev Dattani , James H. Bannock , Zhuping Fei , Roderick Mackenzie , Anne Guilbert , Michelle Vezie , Jenny Nelson , John C. De Mello , Martin Heeney , Joao Cabral , Alisyn Nedoma Journal Of Materials Chemistry A DOI: 10.1039/C4TA03146F Diamond Proposal Number(s): [8339] Show Abstract ▼ Abstract: Block copolymers have the potential to self-assemble into thermodynamically stable nanostructures that are desirable for plastic electronic materials with prolonged lifetimes. Fulfillment of this potential requires the simultaneous optimisation of the spatial organisation and phase behaviour of heterogeneous thin films at the nanoscale. We demonstrate the controlled assembly of an all-conjugated diblock copolymer blended with fullerene. The crystallinity, nanophase separated morphology, and microscopic features are characterised for blends of poly(3-hexylthiophene-block-3-(2-ethylhexyl) thiophene) (P3HT-b-P3EHT) and phenyl-C61-butyric acid methyl ester (PCBM), with PCBM fractions varying from 065 wt%. We find that PCBM induces the P3HT block to crystallise, causing nanophase separation of the block copolymer. Resulting nanostructures range from ordered (lamellae) to disordered, depending on the amount of PCBM. We identify the key design parameters and propose a general mechanism for controlling thin film structure and crystallinity during the processing of semicrystalline block copolymers.	Jul 2014
I07-Surface & interface diffraction	Influence of bridging atom and side chains on the structure and crystallinity of cyclopentadithiophene-benzothiadiazole polymers Anne Guilbert , Jarvist M. Frost , Tiziano Agostinelli , Ellis Pires , Samuele Lilliu , Emyr Macdonald , Jenny Nelson Chemistry Of Materials 26 (2) DOI: 10.1021/cm403410w Show Abstract ▼ Abstract: We use grazing-incidence wide-angle X-ray scattering (GIWAXS) and molecular modeling to understand the difference in crystallization of several cyclopentadithiophene–benzothiadiazole polymer derivatives. We observe using GIWAXS that when the carbon bridging atom is substituted by a silicon atom, the π–π stacking distance is decreased while the lamellar stacking distance is increased. Using molecular modeling, we calculate the potential energy surfaces of an ordered array of oligomers as a function of π–π stacking and lamellar stacking distances and find two local minima for both the carbon and silicon analogues. This finding is consistent with the GIWAXS observations. We suggest that it may be possible to crystallize the carbon and silicon versions in the same crystal structure by varying the processing conditions. We derive new potential parameters from quantum chemical calculations for side chains motions and implement those within a new force field for molecular dynamics. We find that the side chains are more flexible in the case of the silicon bridging atom. We propose that the flexibility enhancement may influence both thermodynamics and kinetics of crystallization and may result in crystallization of the polymer in the first or the second energetically favored crystal structures. This interpretation is supported by the finding of only one minimum in potential energy for longer, less bulky, and, thus, more flexible side chains for the carbon analogue.	Dec 2013
I07-Surface & interface diffraction	Effect of multiple adduct fullerenes on microstructure and phase behavior of P3HT:fullerene blend films for organic solar cells Anne Guilbert , Luke X. Reynolds , Annalisa Bruno , Andrew Maclachlan , Simon P. King , Mark A. Faist , Ellis Pires , J. Emyr Macdonald , Natalie Stingelin , Saif A. Haque , Jenny Nelson Acs Nano 6 (5), 3868 - 3875 DOI: 10.1021/nn204996w Diamond Proposal Number(s): [6319] Show Abstract ▼ Abstract: The bis and tris adducts of [6,6]phenyl-C 61 -butyric acid methyl ester (PCBM) offer lower reduction potentials than PCBM and are therefore expected to offer larger open-circuit voltages and more efficient energy conversion when blended with conjugated polymers in photovoltaic devices in place of PCBM. However, poor photovoltaic device performances are commonly observed when PCBM is replaced with higher- adduct fullerenes. In this work, we use transmission electron microscopy (TEM), steady-state and ultrafast time-resolved photoluminescence spectroscopy (PL), and differential scanning calorimetry (DSC) to probe the microstructural properties of blend films of poly(3-hexylthiophene-2,5-diyl) (P3HT) with the bis and tris adducts of PCBM. TEM and PL indicate that, in as-spun blend films, fullerenes become less soluble in P3HT as the number of adducts increases. PL indicates that upon annealing crystallization leads to phase separation in P3HT:PCBM samples only. DSC studies indicate that the interactions between P3HT and the fullerene become weaker with higher-adduct fullerenes and that all systems exhibit eutectic phase behavior with a eutectic composition being shifted to higher molar fullerene content for higher-adduct fullerenes. We propose two different mechanisms of microstructure development for PCBM and higher-adduct fullerenes. P3HT:PCBM blends, phase segregation is the result of crystallization of either one or both components and is facilitated by thermal treatments. In contrast, for blends containing higher adducts, the phase separation is due to a partial demixing of the amorphous phases. We rationalize the lower photocurrent generation by the higher-adduct fullerene blends in terms of film microstructure.	May 2012
I07-Surface & interface diffraction	Effects of thermal annealing upon the nanomorphology of poly(3-hexylselenophene)-PCBM blends Samuele Lilliu , Tiziano Agostinelli , Eric Verploegen , Ellis Pires , Mark Hampton , Mohammed Al-Hashimi , Martin J. Heeney , Michael F. Toney , Jenny Nelson , J. Emyr Macdonald Macromolecular Rapid Communications 32 (18), 1454 - 1460 DOI: 10.1002/marc.201100330 Show Abstract ▼ Abstract: Grazing incidence X-ray diffraction (GI-XRD) is used to characterize the crystallographic dynamics of low molecular weight (LMW) and high molecular weight (HMW) poly(3-hexylselenophene) (P3HS) films and blend films of P3HS with [6-6-]-phenyl-C61-butyric acid methyl ester (PCBM) as a function of ‘step-by-step’ thermal annealing, from room temperature to 250 °C. The temperature-dependent GIXRD data show how the melting point of P3HS crystallites is decreased by the presence of PCBM. P3HS crystallite domain sizes dramatically increase upon annealing to the P3HS melting temperature. The formation of well-oriented HMW P3HS crystallites with the (100) plane parallel to the substrate (edge-on orientation), when cooled from melt, are observed. We compare the behaviour of P3HS pure and blend films with that of poly(3-hexyl)thiophene (P3HT) pure and PCBM blended films and suggest that the similar temperature dependent behaviour we observe may be a common to polythiophene and related polymers and their blends.	Jul 2011
I07-Surface & interface diffraction	Dynamics of crystallization and disorder during annealing of P3HT/PCBM bulk heterojunctions Samuele Lilliu , Tiziano Agostinelli , Ellis Pires , Mark Hampton , Jenny Nelson , J. Emyr Macdonald Macromolecules 44 (8), 2725 - 2734 DOI: 10.1021/ma102817z Show Abstract ▼ Abstract: A real-time crystallographic analysis of P3HT/PCBM films during thermal annealing is reported, detailing the temporal variation of crystallization, disorder, and orientational spread during the annealing. Five P3HT/PCBM chlorobenzene solutions with different P3HT concentrations (0, 33, 50, 67, 100 wt %) were spin coated on SiO2 substrates. The thick films (?100 nm) were studied during annealing (50 min at 140 °C), with in situ synchrotron grazing incidence X-ray diffraction (GI-XRD) and a sampling time <8 s. For the first time, the evolution of the crystal structure is analyzed taking into account P3HT paracrystallinity. The following were observed: a predominance of edge-on P3HT lamellae in the as-spun and annealed films; changes in concentration-dependent edge-on lamellar orientation spread along the alkyl-stacking direction and paracrystalline disorder after annealing; a permanent lamellar stretching just along the alky-stacking direction after annealing; an increase in the P3HT domain size along only the alkyl-stacking direction for the edge-on lamellae, with dynamics consistent with PCBM acting as a plasticizer for P3HT; and finally, an increase in the PCBM concentration at the sample?air interface. We show that the paracrystalline correction is important to calculate correctly the domain size as deduced from GI-XRD.	Apr 2011

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