1,721,332 research outputs found
Metal Oxide Semiconductors for Dye- and Quantum-Dot-Sensitized Solar Cells
No full textThis Review provides a brief summary of the most recent research developments in the synthesis and application of nanostructured metal oxide semiconductors for dye sensitized and quantum dot sensitized solar cells. In these devices, the wide bandgap semiconducting oxide acts as the photoanode, which provides the scaffold for light harvesters (either dye molecules
or quantum dots) and electron collection. For this reason,
proper tailoring of the optical and electronic properties of the photoanode can significantly boost the functionalities of the operating device. Optimization of the functional properties relies with modulation of the shape and structure of the photoanode, as well as on application of different materials (TiO2, ZnO, SnO2) and/or composite systems, which allow fine tuning of electronic band structure. This aspect is critical because it determines exciton and charge dynamics in the photoelectrochemical system and is strictly connected to the photoconversion efficiency of the solar cell. The different strategies for increasing light harvesting and charge collection, inhibiting charge losses due to recombination phenomena, are reviewed thoroughly, highlighting the benefits
of proper photoanode preparation, and its crucial role in the development of high efficiency dye sensitized and quantum dot sensitized solar cells
The Renaissance of Luminescent Solar Concentrators: The Role of Inorganic Nanomaterials
No full textWhile luminescent solar concentrators (LSCs) have a simple architecture—a transparent matrix embedding a luminescent fluorophore coupled with solar cells at the lateral side of the LSC slab—multiple paths for possible light losses exist. These are inherently interconnected, and in the past, limited the interest in this device, due to the gap between the theoretical possibilities and experimental achievements. This gap was a result, primarily, of the optical features of the luminescent dyes, since conventional organic luminophores are affected by limited performance in LSC devices. The rise of a wide portfolio of optically active inorganic nanomaterials in the last decade provides an alternative to organic dyes and has lead to a renaissance in the role of LSCs among the unconventional solar energy conversion devices. This paper reviews the latest results in the development of LSCs based on different classes of nanomaterials, focusing on the specific features and critically analyzing the pros and cons of the proposed structures. Particular attention is devoted to the role of the luminescence properties, e.g., the Stokes shift and the photoluminescence quantum yield, with respect to the performance of the LSC device. Future challenges to the successful employment of these devices for building integrated photovoltaics are also discussed
TCO nanostructures for dye-sensitized solar cells, Oxide-Based Materials and Devices Conference, OE107 , Part of program track on Optoelectronic Materials and Devices
No full textTailoring the interfacial structure of colloidal "giant" quantum dots for optoelectronic applications
No full textColloidal semiconductor quantum dots (QDs) are promising building blocks for the realization of future optoelectronic technologies, thanks to their size-tunable electronic and optical properties. Among various types of QDs, colloidal "giant" QDs (g-QDs, core/thick-shell) have been widely used in different applications, such as solar cells, light emitting devices, luminescent solar concentrators and photoelectrochemical (PEC) hydrogen production. However, g-QDs have a thick-shell which serves as a physical barrier for electron and hole transfer, leading to a slow charge transfer rate. In this work, we synthesized CdSe/CdSexS1-x/CdS core/shell/shell g-QDs with an intermediate CdSexS1-x alloyed layer. The presence of this interfacial layer largely improves the absorption of CdSe/CdS QDs, particularly in the 300-650 nm range. By engineering the interfacial layer, the holes can leak more into the CdS shell region compared to that of CdSe/CdS QDs. PEC devices based on alloyed g-QDs exhibit a 20% higher saturated photocurrent density (11 ± 0.5 mA cm-2) compared to CdSe/CdS QDs. In addition, after one-hour illumination (100 mW cm-2), the PEC cell based on alloyed g-QDs still exhibits a photocurrent density of 7.5 mA cm-2, maintaining 70% of its initial value. Such alloyed g-QDs are very promising for several emerging optoelectronic applications, where charge separation, transfer and transport play a critical role for the realization of high performance devices
Emerging Strategies to Achieve Interfacial Solar Water Evaporation Rate Greater than 3 kg·m-2·h-1 under One Sun Irradiation
Full text linkSolar water evaporation is vital for addressing global water scarcity, particularly in regions with limited freshwater. Through the utilization of photothermal materials, solar water evaporation harnesses solar radiation to generate heat, which in turn accelerates the evaporation of water, producing clean drinking water. Subsequently, the vapor is condensed to produce fresh water, offering a sustainable solution to water scarcity. This research field has garnered immense scientific interest, with over six thousand publications. Reported solar absorber evaporation rates exceed 100 kg m−2 h−1 under one sun irradiation, far surpassing the theoretical limit of 1.47 kg m−2 h−1 achievable on two-dimensional absorber surfaces, assuming constant latent heat at 2444 J g−1. This review addresses this significant discrepancy in theoretical and practical values. A cut-off of 3 kg m−2 h−1 (under one sun irradiation) is considered to narrow focus, facilitating analysis of high-rate evaporators. Critical challenges and factors contributing to high evaporation rates are discussed, providing comprehensive insights into field advancements.Validerad;2024;Nivå 2;2024-07-03 (joosat);Funder: European Union (PE0000021); Kempe Foundation; Knut och Alice Wallenbergs Stiftelse; Swedish Foundations Consolidator Fellowship; Italian Ministry of University and Research; Full text license: CC BY 4.0;</p
Fast Multifrequency Measurement of Nonlinear Conductance
No full textWe describe a phase-coherent multifrequency lock-in measurement technique that uses the inverse Fourier transform to reconstruct the nonlinear current-voltage characteristic of a nanoscale junction. The method provides separation of the galvanic and displacement currents in the junction and easy cancellation of the parasitic displacement current from the measurement leads. These two features allow us to overcome traditional limitations imposed by the low conductance of the junction and the high capacitance of the leads, thus providing an increase in measurement speed of several orders of magnitude. We demonstrate the method in the context of conductive atomic force microscopy, acquiring current-voltage characteristics at every pixel while scanning at standard imaging speed
Luminescent lanthanide complexes with phosphoramide and arylphosphonic diamide ligands
No full textThe sensitization of Eu(III) luminescence by the phosphoramide and arylphosphonic diamide ligands OP(NMe2)2Ind, OP(NMe2)2Cbz, OP(NMe2)2Ph, OP(NMe2)2(1-Naph) and OP(NMe2)2(2-Naph) (Ind = indol-1-yl; Ph = phenyl; Cbz = carbazol- 9-yl; 1-Naph = naphtalen-1-yl; 2-Naph = naphtalen-2-yl) was verified by coordination to the [Eu(NO3)3] metal fragment. The emission spectra of the corresponding complexes showed only the 5D0 → 7FJ transitions of the metal centre, with the exception of the carbazolyl derivative. Some of the ligands were also able to sensitize Tb(III) luminescence, in agreement with the triplet state energies estimated from the phosphorescence spectra of the analogous Gd(III) nitrates. On the basis of the photoluminescence results achieved using nitrate as ancillary ligand, heptacoordinate Eu(III) complexes having general formula [Eu(β-dike)3L] (β-dike = dibenzoylmethanate, tenoyltrifluoroacetonate; L = phosphoramide or arylphosphomic diamide ligand) were prepared and characterized. All the complexes exhibited bright red emission upon excitation with near-UV and violet-blue light, with intrinsic quantum yields ranging between 18 and 36%
"Effects of Ta/Nb doping and catalysis with gold nanoparticles on titania-based thin films for CO detection".
No full text- …
