A5045027625- Organic Electronics and Photovoltaics
- Organic Light-Emitting Diodes Research
- Molecular Junctions and Nanostructures
- Conducting polymers and applications
- Perovskite Materials and Applications
- Organic and Molecular Conductors Research
- Thin-Film Transistor Technologies
- Advanced Memory and Neural Computing
- Force Microscopy Techniques and Applications
- GaN-based semiconductor devices and materials
- Quantum Dots Synthesis And Properties
- Liquid Crystal Research Advancements
- Advanced Sensor and Energy Harvesting Materials
- Semiconductor materials and interfaces
- Fluid Dynamics and Thin Films
University of Oxford
2018-2024
University of Arizona
2022
University of Florence
2022
Diamond Light Source
2022
Oxfam
2021
Technical University of Denmark
2017-2020
Abstract Simultaneous control over both the energy levels and Fermi level, a key breakthrough for inorganic electronics, has yet to be shown organic semiconductors. Here, level tuning molecular doping are combined demonstrate controlled shifts in ionisation potential of an thin film. This is achieved by p-doping blend two host molecules, zinc phthalocyanine its eight-times fluorinated derivative, with tunable based on mixing ratio. The efficiency found depend ratio, which explained using...
Halide perovskite light-emitting diodes (PeLEDs) exhibit great potential for use in next-generation display technologies. However, scale-up will be challenging due to the requirement of very thin transport layers high efficiencies, which often present spatial inhomogeneities from improper wetting and drying during solution processing. Here, we show how a Al2O3 layer grown by atomic deposition can used preferentially cover regions imperfect hole form an intermixed composite with organic...
Abstract Free charge generation after photoexcitation of donor or acceptor molecules in organic solar cells generally proceeds via (1) formation transfer states and (2) their dissociation into separated states. Research often either focuses on the first component combined effect both processes. Here, we provide evidence that state rather than presents a major bottleneck for free fullerene-based blends with low energetic offsets between singlet We investigate devices based dilute content...
We use the electron spin as a probe to gain insight into mechanism of molecular doping in p-doped zinc phthalocyanine host across broad range temperatures (80–280 K) and concentrations (0–5 wt% F6-TCNNQ).
We report on a method for fabricating balanced hole and electron transport in ambipolar organic field-effect transistors (OFETs) based the co-evaporation of zinc-phthalocyanine (ZnPc) its fluorinated derivative (F8ZnPc). The semiconducting behaviour OFET can be tuned continuously from unipolar p-type, with mobility range (1.7 ± 0.1) × 10−4 cm2/Vs, to n-type, an (1.0 cm2/Vs. Devices pristine ZnPc F8ZnPc show current on/off ratio 105. By co-evaporating p-type n-type F8ZnPc, we fabricate...
Copolymers based on diketopyrrolopyrrole (DPP) cores have attracted a lot of attention because their high p-type as well n-type carrier mobilities in organic field-effect transistors (FETs) and power conversion efficiencies solar cell structures. We report the structural charge transport properties n-dialkyl side-chain-substituted thiophene DPP end-capped with phenyl group (Ph-TDPP-Ph) monomer FETs which were fabricated by vacuum deposition solvent coating. Grazing-incidence X-ray...
The real-time morphological evolution of vacuum-deposited α-sexithiophene (α-6T) on a weakly interacting (glass) substrate at ambient temperature is reported. In situ grazing-incidence small-angle X-ray scattering (GISAXS) enabled the observation nanoscale aggregates, while in wide-angle (GIWAXS) allowed study molecular-scale morphology. GISAXS measurements revealed that α-6T growth proceeds via Stranski–Krastanov mode, whereby 2–4 complete monolayers are deposited, followed by subsequent...
We report on the structure and morphology of 5,5'-bis(naphth-2-yl)-2,2'-bithiophene (NaT2) films in bottom-contact organic field-effect transistors (OFETs) with octadecyltrichlorosilane (OTS) coated SiO2 gate dielectric, characterized by atomic force microscopy (AFM), grazing-incidence X-ray diffraction (GIXRD), electrical transport measurements. Three types devices were investigated NaT2 thin-film deposited either (1) pristine (corresponding to higher surface energy, 47 mJ/m2) or OTS under...
The performance of organic solar cells is strongly governed by the properties photovoltaic active layer. In particular, energetics at donor (D)–acceptor (A) interface dictate charge transfer (CT) states and limit open-circuit voltage. More generally, energetic landscapes in thin films are affected intermolecular, e.g., van der Waals, dipole, quadrupole, interactions that vary with D:A mixing ratio impact energy levels free charges (ionization energy, electron affinity) excitons (singlet, CT...
We report process improvements for the fabrication of single-walled carbon nanotube ethylene-vinyl acetate transparent conductive films. CNT:EVA films demonstrate high resilience against folding and can replace external dopant in a spiro-OMeTAD based hole selective contact n-i-p perovskite solar cells achieving steady-state efficiency 16.3%. The adapted is fully scalable, compared to previous reports (Mazzotta et al., 2018) lowers material cost dramatically improves DC optical conductivity...
The structure of two naphthylene-capped oligothiophene, 5,5′-bis(naphth-2-yl)-2,2′- bi- and tri- thiophene, thin-film field-effect transistor assemblies has been studied using modeling in conjunction with grazing incidence X-ray diffraction. Although the well-known herringbone molecular packing motif is observed these films for both compounds, density functional calculations mechanics give evidence a local polymorphic ordering which molecules can be flipped 180° about long axis. In one case,...
We report on the characterization of growth vacuum-deposited zinc phthalocyanine (ZnPc) thin films glass through a combination in situ grazing incidence x-ray scattering, reflectivity, and atomic force microscopy. found that at room temperature proceeds via formation two structurally unique substrate-induced interfacial layers, followed by $\ensuremath{\gamma}$-ZnPc polymorph thereafter (thickness $\ensuremath{\approx}1.0$ nm). As bulk progresses, substantial out-of-plane lattice strain...
All-Small-Molecule Organic Solar Cells (ASM-OSCs) have reached 17% efficiency. Unlike polymers, SM synthesis is reproducible with controlled quality, making ASM-OSC highly relevant for commercialization. We perform extensive optoelectronic and microstructure characterization on high-performing deposited via solution vacuum thermal evaporation. quantify absorption, voltage losses, charge transport – probed ellipsometry, sensitive EQE, CELIV, respectively. To rationalize differences in carrier...
<title>Abstract</title> Free charge generation in organic solar cells generally proceeds via (1) the formation of transfer (CT) excitons after photoexcitation donor or acceptor molecules, and (2) CT dissociation into separated (CS) state. While efficiency depends on energetic difference between local excitation (LE) singlet states, is determined by barrier CS states. For a long time, research either studied combined effect photocurrents without distinguishing individual processes, primarily...