103 results found
Moia D, Gelmetti I, Calado P, et al., Ionic-to-electronic current amplification in hybrid perovskite solar cells: Ionically gated transistor-interface circuit model explains hysteresis and impedance of mixed conducting devices, Energy and Environmental Science, ISSN: 1754-5692
Mobile ions in hybrid perovskite semiconductors introduce a new degree of freedom to electronic devices suggesting applications beyond photovoltaics. An intuitive device model describing the interplay between ionic and electronic charge transfer is needed to unlock the full potential of the technology. We describe the perovskite-contact interfaces as transistors which couple ionic charge redistribution to energetic barriers controlling electronic injection and recombination. This reveals an amplification factor between the out of phase electronic current and the ionic current. Our findings suggest a strategy to design thin film electronic components with large, tuneable, capacitor-like and inductor-like characteristics. The resulting simple equivalent circuit model, which we verified with time-dependent drift-diffusion simulations of measured impedance spectra, allows a general description and interpretation of perovskite solar cell behaviour.
Calado P, Burkitt D, Yao J, et al., Identifying dominant recombination mechanisms in perovskite solar cells by measuring the transient ideality factor, Physical Review Applied, ISSN: 2331-7019
The light ideality factor determined by measuring the open circuit voltage (VOC) as function of light intensity is often used to identify the dominant recombination mechanism in solar cells. Applying this ‘Suns-VOC’ technique to perovskite cells is problematic since the VOC evolves with time in a way which depends on the previously applied bias (Vpre), bias light intensity, and device architecture/processing. Here we show that the dominant recombination mechanism in two structurally similar CH3NH3PbI3 devices containing either mesoporous Al2O3 or TiO2 layers can be identified from the signature of the transient ideality factor following application of a forward bias, Vpre, to the device in the dark. The transient ideality factor, is measured by monitoring the evolution of VOC as a function of time at different light intensities. The initial values of ideality found using this technique were consistent with estimates of ideality factor obtained from measurements of photoluminescence vs light intensity and electroluminescence vs current density. Time-dependent simulations of the measurement on modelled devices, which include the effects of mobile ionic charge, reveal that this initial value can be correlated to an existing zero-dimensional model while steady-state values must be analysed taking into account the homogeneity of carrier populations throughout the absorber layer. The analysis shows that Shockley Read Hall (SRH) recombination through deep traps at the charge collection interfaces is dominant in both architectures of measured device. Using transient photovoltage measurements directly following illumination on bifacial devices we further show that the perovskite/electron transport layer interface extends throughout the mesoporous TiO2 layer, consistent with a transient ideality signature corresponding to SRH recombination in the bulk of the film. This method will be useful for identifying performance bottlenecks in new variants of perovskite and
Hu Y, Spies LM, Alonso-Alvarez D, et al., 2018, Identifying and controlling phase purity in 2D hybrid perovskite thin films, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 6, Pages: 22215-22225, ISSN: 2050-7488
Shital S, Barnes PRF, Dutta V, 2018, Analysis of four-flux parameters of TiO2 films commonly used in DSSCs, SOLAR ENERGY, Vol: 173, Pages: 530-538, ISSN: 0038-092X
Du T, Kim J, Ngiam J, et al., 2018, Elucidating the Origins of Subgap Tail States and Open-Circuit Voltage in Methylammonium Lead Triiodide Perovskite Solar Cells, ADVANCED FUNCTIONAL MATERIALS, Vol: 28, ISSN: 1616-301X
Du T, Kim J, Ngiam J, et al., Elucidating the origins of sub-gap tail states and open-circuit voltage in methylammonium lead triiodide perovskite solar cells, Advanced Functional Materials, ISSN: 1616-301X
Recombination via sub-gap trap states is considered a limiting factor in the development of organometal halide perovskite solar cells. Here, we demonstrate the impact of active layer crystallinity on the accumulated charge and open-circuit voltage (Voc) in solar cells based on methylammonium lead triiodide (CH3NH3PbI3, MAPI). We show MAPI crystallinity can be systematically tailored by modulating the stoichiometry of the precursor mix, where small quantities of excess methylammonium iodide (MAI) improves crystallinity increasing device Voc by ~200 mV. Using in-situ differential charging and transient photovoltage measurements, charge density and charge carrier recombination lifetime are determined under operational conditions. Increased Voc is correlated to improved active layer crystallinity and a reduction in the density of trap states in MAPI. Photoluminescence spectroscopy shows that an increase in trap states correlates with faster carrier trapping and more non-radiative recombination pathways. We provide fundamental insights into the origin of Voc in perovskite photovoltaics and demonstrate why highly crystalline perovskite films are paramount for high-performance devices.
Giovannitti A, Maria IP, Hanifi D, et al., 2018, The Role of the Side Chain on the Performance of N-type Conjugated Polymers in Aqueous Electrolytes, CHEMISTRY OF MATERIALS, Vol: 30, Pages: 2945-2953, ISSN: 0897-4756
Calado P, Barnes PRF, Azzouzi M, et al., 2018, Driftfusion
An open source drift diffusion code based in MATLAB for simulating solar cells.
Shital S, Swami SK, Barnes P, et al., 2018, Monte Carlo simulation for optimization of a simple and efficient bifacial DSSC with a scattering layer in the middle, SOLAR ENERGY, Vol: 161, Pages: 64-73, ISSN: 0038-092X
Jong U-G, Yu C-J, Ri G-C, et al., 2018, Influence of water intercalation and hydration on chemical decomposition and ion transport in methylammonium lead halide perovskites, Publisher: ROYAL SOC CHEMISTRY
Moss B, Lim KK, Beltram A, et al., 2017, Comparing photoelectrochemical water oxidation, recombination kinetics and charge trapping in the three polymorphs of TiO2, SCIENTIFIC REPORTS, Vol: 7, ISSN: 2045-2322
Belisle RA, Nguyen WH, Bowring AR, et al., 2017, Interpretation of inverted photocurrent transients in organic lead halide perovskite solar cells: proof of the field screening by mobile ions and determination of the space charge layer widths, ENERGY & ENVIRONMENTAL SCIENCE, Vol: 10, Pages: 192-204, ISSN: 1754-5692
Calado P, Telford AM, Bryant D, et al., 2016, Evidence for ion migration in hybrid perovskite solar cells with minimal hysteresis, NATURE COMMUNICATIONS, Vol: 7, ISSN: 2041-1723
Vaissier V, Sakai VG, Li X, et al., 2016, How mobile are dye adsorbates and acetonitrile molecules on the surface of TiO2 nanoparticles? A quasi-elastic neutron scattering study, SCIENTIFIC REPORTS, Vol: 6, ISSN: 2045-2322
Leguy AMA, Goni AR, Frost JM, et al., 2016, Dynamic disorder, phonon lifetimes, and the assignment of modes to the vibrational spectra of methylammonium lead halide perovskites, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 18, Pages: 27051-27066, ISSN: 1463-9076
Moia D, Szumska A, Vaissier V, et al., 2016, Interdye Hole Transport Accelerates Recombination in Dye Sensitized Mesoporous Films, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 138, Pages: 13197-13206, ISSN: 0002-7863
Petrus ML, Hu Y, Moia D, et al., 2016, The Influence of Water Vapor on the Stability and Processing of Hybrid Perovskite Solar Cells Made from Non-Stoichiometric Precursor Mixtures, CHEMSUSCHEM, Vol: 9, Pages: 2699-2707, ISSN: 1864-5631
Flasque M, Van Nhien AN, Moia D, et al., 2016, Consequences of Solid Electrolyte Interphase (SEI) Formation upon Aging on Charge-Transfer Processes in Dye-Sensitized Solar Cells, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 120, Pages: 18991-18998, ISSN: 1932-7447
Cappel UB, Moia D, Bruno A, et al., 2016, Evidence for photo-induced charge separation between dye molecules adsorbed to aluminium oxide surfaces, SCIENTIFIC REPORTS, Vol: 6, ISSN: 2045-2322
Kafizas A, Wang X, Pendlebury SR, et al., 2016, Where Do Photogenerated Holes Go in Anatase:Rutile TiO2? A Transient Absorption Spectroscopy Study of Charge Transfer and Lifetime, JOURNAL OF PHYSICAL CHEMISTRY A, Vol: 120, Pages: 715-723, ISSN: 1089-5639
Leguy AMA, Azarhoosh P, Alonso MI, et al., 2016, Experimental and theoretical optical properties of methylammonium lead halide perovskites, NANOSCALE, Vol: 8, Pages: 6317-6327, ISSN: 2040-3364
Carnie MJ, Troughton J, Regan BO, et al., 2015, Identifying recombination mechanisms through materials development in perovskite solar cells
© 2015 IEEE. Through materials and device developments and by using measurements such as transient photovoltage decay and impedance spectroscopy we have begun to identify recombination mechanisms in perovskite solar cells. At the forefront of our developments is a transparent, indium free, cathode which allows measurements to be made whilst illuminating from both the photoanode side and the cathode side of the device. Recombination is consistently faster when illuminated from the cathode side and we conclude that in this case, as charge carriers are generated closer to the perovskite/SPIRO-OMeTAD interface, interfacial recombination is a significant contributor to voltage losses within the device.
Vaissier V, Frost JM, Barnes PRF, et al., 2015, Influence of Intermolecular Interactions on the Reorganization Energy of Charge Transfer between Surface-Attached Dye Molecules, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 119, Pages: 24337-24341, ISSN: 1932-7447
Moia D, Leijtens T, Noel N, et al., 2015, Dye Monolayers Used as the Hole Transporting Medium in Dye-Sensitized Solar Cells, ADVANCED MATERIALS, Vol: 27, Pages: 5889-5894, ISSN: 0935-9648
Brivio F, Frost JM, Skelton JM, et al., 2015, Lattice dynamics and vibrational spectra of the orthorhombic, tetragonal, and cubic phases of methylammonium lead iodide, PHYSICAL REVIEW B, Vol: 92, ISSN: 1098-0121
Bryant D, Wheeler S, O'Regan BC, et al., 2015, Observable Hysteresis at Low Temperature in "Hysteresis Free" Organic-Inorganic Lead Halide Perovskite Solar Cells, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, Vol: 6, Pages: 3190-3194, ISSN: 1948-7185
Moia D, Cappel UB, Leijtens T, et al., 2015, The Role of Hole Transport between Dyes in Solid-State Dye-Sensitized Solar Cells, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 119, Pages: 18975-18985, ISSN: 1932-7447
Eames C, Frost JM, Barnes PRF, et al., 2015, Ionic transport in hybrid lead iodide perovskite solar cells, NATURE COMMUNICATIONS, Vol: 6, ISSN: 2041-1723
Leguy AMA, Hu Y, Campoy-Quiles M, et al., 2015, Reversible Hydration of CH(3)NH(3)Pbl(3) in Films, Single Crystals, and Solar Cells, CHEMISTRY OF MATERIALS, Vol: 27, Pages: 3397-3407, ISSN: 0897-4756
Leguy AMA, Frost JM, McMahon AP, et al., 2015, The dynamics of methylammonium ions in hybrid organic-inorganic perovskite solar cells, NATURE COMMUNICATIONS, Vol: 6, ISSN: 2041-1723
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