Publications
Results
- Showing results for:
- Reset all filters
Search results
-
Journal articleAltendorf SG, Reisner A, Tam B, et al., 2018,
Strong modification of thin film properties due to screening across the interface
, PHYSICAL REVIEW B, Vol: 97, ISSN: 2469-9950- Author Web Link
- Cite
- Citations: 3
-
Journal articleRohr J, Shi X, Haque S, et al., 2018,
Charge transport in Spiro-OMeTAD investigated through space-charge-limited current measurements
, Physical Review Applied, Vol: 9, ISSN: 2331-7019Extracting charge-carrier mobilities for organic semiconductors from space-charge-limited conduction measurements is complicated in practice by nonideal factors such as trapping in defects and injection barriers. Here, we show that by allowing the bandlike charge-carrier mobility, trap characteristics, injection barrier heights, and the shunt resistance to vary in a multiple-trapping drift-diffusion model, a numerical fit can be obtained to the entire current density–voltage curve from experimental space-charge-limited current measurements on both symmetric and asymmetric 2,2′,7,7′-tetrakis(N,N-di-4-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) single-carrier devices. This approach yields a bandlike mobility that is more than an order of magnitude higher than the effective mobility obtained using analytical approximations, such as the Mott-Gurney law and the moving-electrode equation. It is also shown that where these analytical approximations require a temperature-dependent effective mobility to achieve fits, the numerical model can yield a temperature-, electric-field-, and charge-carrier-density-independent mobility. Finally, we present an analytical model describing trap-limited current flow through a semiconductor in a symmetric single-carrier device. We compare the obtained charge-carrier mobility and trap characteristics from this analytical model to the results from the numerical model, showing excellent agreement. This work shows the importance of accounting for traps and injection barriers explicitly when analyzing current density–voltage curves from space-charge-limited current measurements.
-
Journal articleFei Z, Eisner FD, Jiao X, et al., 2018,
Correction: An alkylated indacenodithieno[3,2-b] thiophene-based nonfullerene acceptor with high crystallinity exhibiting single junction solar cell efficiencies greater than 13% with low voltage losses (vol 30, 2018)
, Advanced Materials, Vol: 30, ISSN: 0935-9648 -
Journal articleLee HKH, Telford AM, Rohr JA, et al., 2018,
The role of fullerenes in the environmental stability of polymer: fullerene solar cells
, Energy and Environmental Science, Vol: 11, Pages: 417-428, ISSN: 1754-5692Environmental stability is a common challenge for the commercialisation of low cost, encapsulation-free organic opto-electronic devices. Understanding the role of materials degradation is the key to address this challenge, but most such studies have been limited to conjugated polymers. Here we quantitatively study the role of the common fullerene derivative PCBM in limiting the stability of benchmark organic solar cells, showing that a minor fraction (<1%) of photo-oxidised PCBM, induced by short exposure to either solar or ambient laboratory lighting conditions in air, consistent with typical processing and operating conditions, is sufficient to compromise device performance severely. We identify the effects of photo-oxidation of PCBM on its chemical structure, and connect this to specific changes in its electronic structure, which significantly alter the electron transport and recombination kinetics. The effect of photo-oxidation on device current–voltage characteristics, electron mobility and density of states could all be explained with the same model of photoinduced defects acting as trap states. Our results demonstrate that the photochemical instability of PCBM and chemically similar fullerenes remains a barrier for the commercialisation of organic opto-electronic devices.
-
Journal articleRohr JA, Moia D, Haque SA, et al., 2018,
Exploring the validity and limitations of the Mott-Gurney law for charge-carrier mobility determination of semiconducting thin-films
, Journal of Physics: Condensed Matter, Vol: 30, ISSN: 0953-8984Using drift-diffusion simulations, we investigate the voltage dependence of the dark current in single carrier devices, typically used to determine charge-carrier mobilities. For both low and high voltages, the current increases linearly with the applied voltage. Whereas the linear current at low voltages is mainly due to space charge in the middle of the device, the linear current at high voltage is caused by charge-carrier saturation due to a high degree of injection. As a consequence, the current density at these voltages does not follow the classical square law derived by Mott and Gurney, and we show that for trap-free devices, only for intermediate voltages, a space-charge-limited drift current can be observed with a slope that approaches two. We show that, depending on the thickness of the semiconductor layer and the size of the injection barriers, the two linear current-voltage regimes can dominate the whole voltage range, and the intermediate Mott-Gurney regime can shrink or disappear. In this case, which will especially occur for thicknesses and injection barriers typical for single-carrier devices used to probe organic semiconductors, a meaningful analysis using the Mott-Gurney law will become unachievable, because a square-law fit can no longer be achieved, resulting in the mobility being substantially underestimated. General criteria for when to expect deviations from the Mott-Gurney law when used for analysis of intrinsic semiconductors are discussed.
-
Journal articleFei Z, Eisner FD, Jiao X, et al., 2018,
An alkylated indacenodithieno[3,2-b]thiophene-based nonfullerene acceptor with high crystallinity exhibiting single junction solar cell efficiencies greater than 13% with low voltage losses
, Advanced Materials, Vol: 30, Pages: 1-7, ISSN: 0935-9648A new synthetic route, to prepare an alkylated indacenodithieno[3,2-b]thiophene-based nonfullerene acceptor (C8-ITIC), is reported. Compared to the reported ITIC with phenylalkyl side chains, the new acceptor C8-ITIC exhibits a reduction in the optical band gap, higher absorptivity, and an increased propensity to crystallize. Accordingly, blends with the donor polymer PBDB-T exhibit a power conversion efficiency (PCE) up to 12.4%. Further improvements in efficiency are found upon backbone fluorination of the donor polymer to afford the novel material PFBDB-T. The resulting blend with C8-ITIC shows an impressive PCE up to 13.2% as a result of the higher open-circuit voltage. Electroluminescence studies demonstrate that backbone fluorination reduces the energy loss of the blends, with PFBDB-T/C8-ITIC-based cells exhibiting a small energy loss of 0.6 eV combined with a high JSCof 19.6 mA cm-2.
-
Journal articleRice B, LeBlanc LM, Otero-de-la-Roza A, et al., 2018,
A computational exploration of the crystal energy and charge-carrier mobility landscapes of the chiral [6]helicene molecule
, Nanoscale, Vol: 10, Pages: 1865-1876, ISSN: 2040-3364The potential of a given π-conjugated organic molecule in an organic semiconductor device is highly dependent on molecular packing, as it strongly influences the charge-carrier mobility of the material. Such solid-state packing is sensitive to subtle differences in their intermolecular interactions and is challenging to predict. Chirality of the organic molecule adds an additional element of complexity to intuitive packing prediction. Here we use crystal structure prediction to explore the lattice-energy landscape of a potential chiral organic semiconductor, [6]helicene. We reproduce the experimentally observed enantiopure crystal structure and explain the absence of an experimentally observed racemate structure. By exploring how the hole and electron-mobility varies across the energy–structure–function landscape for [6]helicene, we find that an energetically favourable and frequently occurring packing motif is particularly promising for electron-mobility, with a highest calculated mobility of 2.9 cm2 V−1 s−1 (assuming a reorganization energy of 0.46 eV). We also calculate relatively high hole-mobility in some structures, with a highest calculated mobility of 2.0 cm2 V−1 s−1 found for chains of helicenes packed in a herringbone fashion. Neither the energetically favourable nor high charge-carrier mobility packing motifs are intuitively obvious, and this demonstrates the utility of our approach to computationally explore the energy–structure–function landscape for organic semiconductors. Our work demonstrates a route for the use of computational simulations to aid in the design of new molecules for organic electronics, through the a priori prediction of their likely solid-state form and properties.
-
Journal articleFew SPM, Schmidt O, Offer GJ, et al., 2018,
Prospective improvements in cost and cycle life of off-grid lithium-ion battery packs: An analysis informed by expert elicitations
, Energy Policy, Vol: 114, Pages: 578-590, ISSN: 0301-4215This paper presents probabilistic estimates of the 2020 and 2030 cost and cycle life of lithium-ion battery (LiB) packs for off-grid stationary electricity storage made by leading battery experts from academia and industry, and insights on the role of public research and development (R&D) funding and other drivers in determining these. By 2020, experts expect developments to arise chiefly through engineering, manufacturing and incremental chemistry changes, and expect additional R&D funding to have little impact on cost. By 2030, experts indicate that more fundamental chemistry changes are possible, particularly under higher R&D funding scenarios, but are not inevitable. Experts suggest that significant improvements in cycle life (eg. doubling or greater) are more achievable than in cost, particularly by 2020, and that R&D could play a greater role in driving these. Experts expressed some concern, but had relatively little knowledge, of the environmental impact of LiBs. Analysis is conducted of the implications of prospective LiB improvements for the competitiveness of solar photovoltaic + LiB systems for off-grid electrification.
-
Book chapterTam B, Garbarino S, Guay D, 2018,
NH<inf>3</inf> oxidation on well-defined surfaces and proxies of the same
, Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, Pages: 752-760The current state of knowledge for the electrooxidation of ammonia on Pt electrodes with well-defined surfaces is discussed. From seminal studies on single crystal electrodes in alkaline media, the reaction is known to be highly dependent upon the surface structure. Pt surfaces with (100) orientation are the most active, while surfaces with (111) and (110) orientation have greatly reduced reactivity. Wide terraces of (100) orientation are also found to be significantly more active than (100) step domains. We describe NH3 electrooxidation on cubic nanoparticles enclosed with six facets of (100) atoms and highlight convenient methods which produce Pt catalysts with sufficiently tuned (100) surface structure such as epitaxial growth of Pt thin layers and Pt electrodeposition; both methods offer a low cost alternative to proxy the synthesis of single crystal (100) Pt catalysts. Emerging, bimetallic catalysts are anticipated to shed light on the ammonia oxidation reaction mechanism and further improve the reaction by reducing self-poisoning of the reaction.
-
Journal articleWadsworth A, Hamid Z, Bidwell M, et al., 2018,
Progress in Poly (3-Hexylthiophene) Organic Solar Cells and the Influence of Its Molecular Weight on Device Performance
, ADVANCED ENERGY MATERIALS, Vol: 8, ISSN: 1614-6832 -
Journal articlePrashanthan K, Thivakarasarma T, Ravirajan P, et al., 2017,
Enhancement of hole mobility in hybrid titanium dioxide/poly(3-hexylthiophene) nanocomposites by employing an oligothiophene dye as an interface modifier
, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 5, Pages: 11758-11762, ISSN: 2050-7526 -
Working paperMoia D, Giovannitti A, Szumska AA, et al., 2017,
A salt water battery with high stability and charging rates made from solution processed conjugated polymers with polar side chains
, Publisher: arXivWe report a neutral salt water based battery which uses p-type and n-typesolution processed polymer films as the cathode and the anode of the cell. Thespecific capacity of the electrodes (approximately 30 mAh cm-3) is achieved viaformation of bipolarons in both the p-type and n-type polymers. By engineeringethylene glycol and zwitterion based side chains attached to the polymerbackbone we facilitate rapid ion transport through the non-porous polymerfilms. This, combined with efficient transport of electronic charge via theconjugated polymer backbones, allowed the films to maintain constant capacityat high charge and discharge rates (>1000 C-rate). The electrodes also showgood stability during electrochemical cycling (less than 30% decrease incapacity over >1000 cycles) and an output voltage up to 1.4 V. The performanceof these semiconducting polymers with polar side-chains demonstrates thepotential of this material class for fast-charging, water based electrochemicalenergy storage devices.
-
Journal articleSchmidt O, Gambhir A, Staffell IL, et al., 2017,
Future cost and performance of water electrolysis: An expert elicitation study
, International Journal of Hydrogen Energy, Vol: 42, Pages: 30470-30492, ISSN: 0360-3199The need for energy storage to balance intermittent and inflexible electricity supply with demand is driving interest in conversion of renewable electricity via electrolysis into a storable gas. But, high capital cost and uncertainty regarding future cost and performance improvements are barriers to investment in water electrolysis. Expert elicitations can support decision-making when data are sparse and their future development uncertain. Therefore, this study presents expert views on future capital cost, lifetime and efficiency for three electrolysis technologies: alkaline (AEC), proton exchange membrane (PEMEC) and solid oxide electrolysis cell (SOEC). Experts estimate that increased R&D funding can reduce capital costs by 0–24%, while production scale-up alone has an impact of 17–30%. System lifetimes may converge at around 60,000–90,000 h and efficiency improvements will be negligible. In addition to innovations on the cell-level, experts highlight improved production methods to automate manufacturing and produce higher quality components. Research into SOECs with lower electrode polarisation resistance or zero-gap AECs could undermine the projected dominance of PEMEC systems. This study thereby reduces barriers to investment in water electrolysis and shows how expert elicitations can help guide near-term investment, policy and research efforts to support the development of electrolysis for low-carbon energy systems.
-
Journal articleBabacan O, Ratnam EL, Disfani VR, et al., 2017,
Distributed energy storage system scheduling considering tariff structure, energy arbitrage and solar PV penetration
, Applied Energy, Vol: 205, Pages: 1384-1393, ISSN: 0306-2619We develop a new convex optimization (CO)-based charge/discharge scheduling algorithm for distributed energy storage systems (ESSs) co-located with solar photovoltaic (PV) systems. The CO-based scheduling algorithm minimizes the monthly electricity expenses of a customer who owns an ESS and incorporates both a time-of-use volumetric tariff and a demand charge tariff. Further, we propose the novel idea of a “supply charge” tariff that incentivizes ESS customers to store excess solar PV generation that may otherwise result in reverse power flow in the distribution grid. By means of a case study we observe the CO-based daily charge/discharge schedules reduce (1) peak net demand (that is, load minus PV generation) of the customer, (2) power fluctuations in the customer net demand profile, and (3) the reliance of the customer on the grid by way of promoting energy self-consumption of local solar PV generation. Two alternate methods for behind-the-meter ESS scheduling are considered as benchmarks for cost minimization, peak net demand reduction, and mitigation of net demand fluctuations. The algorithm is tested using real 30-min interval residential load and solar data of 53 customers over 2-years. Results show that the CO-based scheduling algorithm provides mean peak net demand reductions between 46% and 64%, reduces mean net demand fluctuations by 25–49%, and increases the mean solar PV self-consumption between 24% and 39% when compared to a customer without an ESS. Introduction of a supply charge reduces the maximum solar PV power supply to the grid by 19% on average and does not financially impact ESS owners.
-
Journal articleMiller TS, Suter TM, Telford AM, et al., 2017,
Single crystal, luminescent carbon nitride nanosheets formed by spontaneous dissolution
, Nano Letters, Vol: 17, Pages: 5891-5896, ISSN: 1530-6984A primary method for the production of 2D nanosheets is liquid-phase delamination from their 3D layered bulk analogues. Most strategies currently achieve this objective by significant mechanical energy input or chemical modification but these processes are detrimental to the structure and properties of the resulting 2D nanomaterials. Bulk poly(triazine imide) (PTI)-based carbon nitrides are layered materials with a high degree of crystalline order. Here, we demonstrate that these semiconductors are spontaneously soluble in select polar aprotic solvents, that is, without any chemical or physical intervention. In contrast to more aggressive exfoliation strategies, this thermodynamically driven dissolution process perfectly maintains the crystallographic form of the starting material, yielding solutions of defect-free, hexagonal 2D nanosheets with a well-defined size distribution. This pristine nanosheet structure results in narrow, excitation-wavelength-independent photoluminescence emission spectra. Furthermore, by controlling the aggregation state of the nanosheets, we demonstrate that the emission wavelengths can be tuned from narrow UV to broad-band white. This has potential applicability to a range of optoelectronic devices.
-
Journal articleNelson J, 2017,
A map to find winners
, NATURE MATERIALS, Vol: 16, Pages: 969-970, ISSN: 1476-1122 -
Conference paperSandwell P, Ekins-Daukes N, Nelson J, 2017,
What are the greatest opportunities for PV to contribute to rural development?
, SNEC 11th International Photovoltaic Power Generation Conference and Exhibition (SNEC), Publisher: Elsevier Science BV, Pages: 139-146, ISSN: 1876-6102Minigrid systems powered by solar photovoltaics and battery storage are being deployed around the world to provide basic energy access and facilitate economic development. We use a minigrid simulation and optimisation tool that we have developed to assess various minigrid options in meeting the growing electricity demand of a community in rural Uttar Pradesh, India, in terms of the reliability of the service they provide, the cost of electricity, and total greenhouse gas emissions. We assess the breakeven distance at which off-grid minigrids are favourable in comparison to extending an unreliable grid network with a minigrid backup system, both with and without a carbon price. We suggest that policy recommendations that would encourage the use of minigrids for sustainable rural development, for example allowing subsidies to be available for system expansions and minimum service reliability requirements.
-
Journal articleGuilbert AAY, Zbiri M, Dunbar ADF, et al., 2017,
Quantitative Analysis of the Molecular Dynamics of P3HT:PCBM Bulk Heterojunction
, Journal of Physical Chemistry B, Vol: 121, Pages: 9073-9080, ISSN: 1520-5207The 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 regioregular 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 250–360 K. 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 chains tend to wrap around PCBM molecules 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, the plasticization of PCBM, and the partial miscibility of P3HT and PCBM.
-
Journal articleYang H, Tam B, Colovic M, et al., 2017,
Addressing Chirality in the Structure and Synthesis of [<SUP>18</SUP>F]5-Fluoroaminosuberic Acid ([<SUP>18</SUP>F]FASu)
, CHEMISTRY-A EUROPEAN JOURNAL, Vol: 23, Pages: 11100-11107, ISSN: 0947-6539- Author Web Link
- Cite
- Citations: 6
-
Journal articleRodriguez-Martinez X, Vezie MS, Shi X, et al., 2017,
Quantifying local thickness and composition in thin films of organic photovoltaic blends by Raman scattering
, Journal of Materials Chemistry C, Vol: 5, Pages: 7270-7282, ISSN: 2050-7526We report a methodology based on Raman spectroscopy that enables the non-invasive and fast quantitative determination of local thickness and composition in thin films (from a few monolayers to hundreds of nm) of one or more components. We apply our methodology to blends of organic conjugated materials relevant in the field of organic photovoltaics. As a first step, we exploit the transfer-matrix formalism to describe the Raman process in thin films including reabsorption and interference effects of the incoming and scattered electric fields. This allows determining the effective solid-state Raman cross-section of each material by studying the dependence of the Raman intensity on film thickness. These effective cross sections are then used to estimate the local thickness and composition in a series of polymer:fullerene blends. We find that the model is accurate within ±10 nm in thickness and ±5 vol% in composition provided that (i) the film thickness is kept below the thickness corresponding to the first maximum of the calculated Raman intensity oscillation; (ii) the materials making up the blend show close enough effective Raman cross-sections; and (iii) the degree of order attained by the conjugated polymer in the blend is similar to that achieved when cast alone. Our methodology opens the possibility of making quantitative maps of composition and thickness over large areas (from microns to centimetres squared) with diffraction-limited resolution and in any multi-component system based thin film technology.
-
Journal articleSpeller EM, McGettrick JD, Rice B, et al., 2017,
Impact of Aggregation on the Photochemistry of Fullerene Films: Correlating Stability to Triplet Exciton Kinetics
, ACS APPLIED MATERIALS & INTERFACES, Vol: 9, Pages: 22739-22747, ISSN: 1944-8244 -
Journal articleFew SPM, Chia C, Teo D, et al., 2017,
The impact of chemical structure and molecular packing on the electronic polarisation of fullerene arrays
, Physical Chemistry Chemical Physics, Vol: 19, Pages: 18709-18720, ISSN: 1463-9084Electronic polarisation contributes to the electronic landscape as seen by separating charges in organic materials. The nature of electronic polarisation depends on the polarisability, density, and arrangement of polarisable molecules. In this paper, we introduce a microscopic, coarse-grained model in which we treat each molecule as a polarisable site, and use an array of such polarisable dipoles to calculate the electric field and associated energy of any arrangement of charges in the medium. The model incorporates chemical structure via the molecular polarisability and molecular packing patterns via the structure of the array. We use this model to calculate energies of charge pairs undergoing separation in finite fullerene lattices of different chemical and crystal structures. The effective dielectric constants that we estimate from this approach are in good quantitative agreement with those measured experimentally in C60 and phenyl-C61-butyric acid methyl ester (PCBM) films, but we find significant differences in dielectric constant depending on packing and on direction of separation, which we rationalise in terms of density of polarisable fullerene cages in regions of high field. In general, we find lattices containing molecules of more isotropic polarisability tensors exhibit higher dielectric constants. By exploring several model systems we conclude that differences in molecular polarisability (and therefore, chemical structure) appear to be less important than differences in molecular packing and separation direction in determining the energetic landscape for charge separation. We note that the results are relevant for finite lattices, but not necessarily for infinite systems. We propose that the model could be used to design molecular systems for effective electronic screening.
-
Journal articleWheeler SGM, Bryant D, Troughton J, et al., 2017,
Transient optoelectronic analysis of the impact of material energetics and recombination kinetics on the open-circuit voltage of hybrid perovskite solar cells
, Journal of Physical Chemistry C, Vol: 121, Pages: 13496-13506, ISSN: 1932-7455Transient optoelectronic measurements were used to evaluate the factors determining the open-circuit voltage of a series of planar photovoltaic devices based on hybrid perovskite layers with varying iodine/bromine ratios. Employing differential charging and transient photovoltage measurements, we used a simple device model based on the charge-carrier-density dependence of nongeminate recombination to re-create correctly not only the measured device open-circuit voltage (VOC) as a function of light intensity but also its dependence on bromine substitution. The 173 (±7) mV increase in device voltage observed with 20% bromine substitution is shown to result from a 227 (±8) mV increase in effective electronic band gap, which was offset in part by a 56 (±5) mV voltage loss due to faster carrier recombination. The faster recombination following 20% bromine substitution can be avoided by indene–C60 bisadduct (ICBA) substitution into the [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) electron-collection layer, resulting in a further 73 (±7) mV increase in device VOC. These results are consistent with surface recombination losses at the perovskite/fullerene interface being the primary limitation on the VOC output of bromine-substituted devices. This study thus presents, and experimentally validates, a simple model for the device physics underlying voltage generation in such perovskite-based solar cells and demonstrates that this approach can provide key insights into factors limiting this voltage output as a function of material energetics.
-
Journal articleSteiner F, Poelking C, Niedzialek D, et al., 2017,
Influence of orientation mismatch on charge transport across grain boundaries in tri-isopropylsilylethynyl (TIPS) pentacene thin films
, Physical Chemistry Chemical Physics, Vol: 19, Pages: 10854-10862, ISSN: 1463-9076We present a multi-scale model for charge transport across grain boundaries in molecular electronic materials that incorporates packing disorder, electrostatic and polarisation effects. We choose quasi two-dimensional films of tri-isopropylsilylethynyl pentacene (TIPS-P) as a model system representative of technologically relevant crystalline organic semiconductors. We use atomistic molecular dynamics, with a force-field specific for TIPS-P, to generate and equilibrate polycrystalline two-dimensional thin films. The energy landscape is obtained by calculating contributions from electrostatic interactions and polarization. The variation in these contributions leads to energetic barriers between grains. Subsequently, charge transport is simulated using a kinetic Monte-Carlo algorithm. Two-grain systems with varied mutual orientation are studied. We find relatively little effect of long grain boundaries due to the presence of low impedance pathways. However, effects could be more pronounced for systems with limited inter-grain contact areas. Furthermore, we present a lattice model to generalize the model for small molecular systems. In the general case, depending on molecular architecture and packing, grain boundaries can result in interfacial energy barriers, traps or a combination of both with qualitatively different effects on charge transport.
-
Journal articleBright JM, Babacan O, Kleissl J, et al., 2017,
A synthetic, spatially decorrelating solar irradiance generator and application to a LV grid model with high PV penetration
, SOLAR ENERGY, Vol: 147, Pages: 83-98, ISSN: 0038-092X -
Journal articleBabacan O, Torre W, Kleissl J, 2017,
Siting and sizing of distributed energy storage to mitigate voltage impact by solar PV in distribution systems
, SOLAR ENERGY, Vol: 146, Pages: 199-208, ISSN: 0038-092X -
Journal articleBaran D, Tuladhar S, Economopoulos SP, et al., 2017,
Photovoltaic limitations of BODIPY:fullerene based bulk heterojunction solar cells
, SYNTHETIC METALS, Vol: 226, Pages: 25-30, ISSN: 0379-6779 -
Journal articleHermerschmidt F, Savva A, Georgiou E, et al., 2017,
Influence of the Hole Transporting Layer on the Thermal Stability of Inverted Organic Photovoltaics Using Accelerated-Heat Lifetime Protocols
, ACS APPLIED MATERIALS & INTERFACES, Vol: 9, Pages: 14136-14144, ISSN: 1944-8244 -
Journal articleRohr J, Nelson J, Kirchartz T, 2017,
On the correct interpretation of the low voltage region in intrinsic single-carrier devices
, Journal of Physics: Condensed Matter -
Journal articleKumar N, Zoladek-Lemanczyk A, Guilbert AAY, et al., 2017,
Simultaneous topographical, electrical and optical microscopy of optoelectronic devices at the nanoscale
, Nanoscale, Vol: 9, Pages: 2723-2731, ISSN: 2040-3364Novel optoelectronic devices rely on complex nanomaterial systems where the nanoscale morphology and local chemical composition are critical to performance. However, the lack of analytical techniques that can directly probe these structure–property relationships at the nanoscale presents a major obstacle to device development. In this work, we present a novel method for non-destructive, simultaneous mapping of the morphology, chemical composition and photoelectrical properties with <20 nm spatial resolution by combining plasmonic optical signal enhancement with electrical-mode scanning probe microscopy. We demonstrate that this combined approach offers subsurface sensitivity that can be exploited to provide molecular information with a nanoscale resolution in all three spatial dimensions. By applying the technique to an organic solar cell device, we show that the inferred surface and subsurface composition distribution correlates strongly with the local photocurrent generation and explains macroscopic device performance. For instance, the direct measurement of fullerene phase purity can distinguish between high purity aggregates that lead to poor performance and lower purity aggregates (fullerene intercalated with polymer) that result in strong photocurrent generation and collection. We show that the reliable determination of the structure–property relationship at the nanoscale can remove ambiguity from macroscopic device data and support the identification of the best routes for device optimisation. The multi-parameter measurement approach demonstrated herein is expected to play a significant role in guiding the rational design of nanomaterial-based optoelectronic devices, by opening a new realm of possibilities for advanced investigation via the combination of nanoscale optical spectroscopy with a whole range of scanning probe microscopy modes.
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.