Author
Germà Garcia-Belmonte
Other affiliations: Bar-Ilan University, University of Sheffield, Complutense University of Madrid
Bio: Germà Garcia-Belmonte is an academic researcher from James I University. The author has contributed to research in topics: Capacitance & Perovskite (structure). The author has an hindex of 65, co-authored 219 publications receiving 16980 citations. Previous affiliations of Germà Garcia-Belmonte include Bar-Ilan University & University of Sheffield.
Papers published on a yearly basis
Papers
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TL;DR: In this paper, the main features of the characteristic impedance spectra of dye-sensitized solar cells are described in a wide range of potential conditions: from open to short circuit.
1,123 citations
TL;DR: The interpretation of the impedance parameters for determining the internal features of the device, concerning the carrier distribution, materials properties such as the density of states and/or doping of the semiconductors, and the match of energy levels for photoinduced charge generation and separation are emphasized.
Abstract: We review the application of impedance spectroscopy in dye-sensitized solar cells, quantum dot-sensitized solar cells and organic bulk heterojunction solar cells. We emphasize the interpretation of the impedance parameters for determining the internal features of the device, concerning the carrier distribution, materials properties such as the density of states and/or doping of the semiconductors, and the match of energy levels for photoinduced charge generation and separation. Another central task is the determination of recombination mechanisms from the measured resistances, and the factors governing the device performance by combined analysis of resistances as a function of voltage and current–voltage curves.
1,046 citations
TL;DR: In this paper, the authors summarize the main models that describe the lifetime dependence on bias voltage or carrier density, and find that there are two complementary approaches to clarify the structure of the lifetime.
Abstract: The electron lifetime τn in dye-sensitized solar cells (DSC) is a central quantity to determine the recombination dynamics in the solar cell. It can be measured by several methods: impedance spectroscopy, IMVS, stepped time transients, and open-circuit voltage decays. The paper aims at a better understanding of this fundamental parameter. We summarize the main models that describe the lifetime dependence on bias voltage or carrier density, and find that there are two complementary approaches to clarify the structure of the lifetime. The first is to treat the lifetime as a product of the chemical capacitance and recombination resistance. This approach is important because the resistance largely determines steady state operation characteristics of the solar cell close to open-circuit voltage. The second approach is based on a kinetic model that describes in detail the different processes governing the decay of the carrier population in a measurement of τn. The lifetime is composed of a trapping factor and a...
700 citations
TL;DR: A giant dielectric constant (GDC) phenomenon is found in organic-inorganic lead trihalide perovskites consisting on a low frequency dielectrics constant in the dark of the order of ε0 = 1000 and an unprecedented behavior in whichε0 further increases under illumination or by charge injection at applied bias is found.
Abstract: Organic–inorganic lead trihalide perovskites have emerged as an outstanding photovoltaic material that demonstrated a high 17.9% conversion efficiency of sunlight to electricity in a short time. We have found a giant dielectric constant (GDC) phenomenon in these materials consisting on a low frequency dielectric constant in the dark of the order of e0 = 1000. We also found an unprecedented behavior in which e0 further increases under illumination or by charge injection at applied bias. We observe that e0 increases nearly linearly with the illumination intensity up to an additional factor 1000 under 1 sun. Measurement of a variety of samples of different morphologies, compositions, and different types of contacts shows that the GDC is an intrinsic property of MAPbX3 (MA = CH3NH3+). We hypothesize that the large dielectric response is induced by structural fluctuations. Photoinduced carriers modify the local unit cell equilibrium and change the polarizability, assisted by the freedom of rotation of MA. The ...
645 citations
TL;DR: In this article, the diffusion and recombination in an absorber blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) with indium tin oxide (ITO) and aluminium contacts have been analyzed in the dark by means of impedance spectroscopy.
547 citations
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TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.
Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …
33,785 citations
9,432 citations
TL;DR: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency as mentioned in this paper, and many DSC research groups have been established around the world.
Abstract: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...
8,707 citations
TL;DR: The use of a solid hole conductor dramatically improved the device stability compared to (CH3NH3)PbI3 -sensitized liquid junction cells.
Abstract: We report on solid-state mesoscopic heterojunction solar cells employing nanoparticles (NPs) of methyl ammonium lead iodide (CH3NH3)PbI3 as light harvesters. The perovskite NPs were produced by reaction of methylammonium iodide with PbI2 and deposited onto a submicron-thick mesoscopic TiO2 film, whose pores were infiltrated with the hole-conductor spiro-MeOTAD. Illumination with standard AM-1.5 sunlight generated large photocurrents (JSC) exceeding 17 mA/cm2, an open circuit photovoltage (VOC) of 0.888 V and a fill factor (FF) of 0.62 yielding a power conversion efficiency (PCE) of 9.7%, the highest reported to date for such cells. Femto second laser studies combined with photo-induced absorption measurements showed charge separation to proceed via hole injection from the excited (CH3NH3)PbI3 NPs into the spiro-MeOTAD followed by electron transfer to the mesoscopic TiO2 film. The use of a solid hole conductor dramatically improved the device stability compared to (CH3NH3)PbI3 -sensitized liquid junction cells.
6,751 citations
TL;DR: The field of photocatalysis can be traced back more than 80 years to early observations of the chalking of titania-based paints and to studies of the darkening of metal oxides in contact with organic compounds in sunlight as discussed by the authors.
5,729 citations