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solar energy

Matthew J Turnbull, Daniel Vaccarello, Yun Mui Yiu, Tsun-Kong Sham, Zhifeng Ding
Solar cell performance is most affected by the quality of the light absorber layer. For thin-film devices, this becomes a two-fold problem of maintaining a low-cost design with well-ordered nanocrystal (NC) structure. The use of Cu2ZnSnS4 (CZTS) NCs as the light absorber films forms an ideal low-cost design, but the quaternary structure makes it difficult to maintain a well-ordered layer without the use of high-temperature treatments. There is little understanding of how CZTS NC structures affect the photoconversion efficiency, the charge-carriers, and therefore the performance of the device manufactured from it...
November 28, 2016: Journal of Chemical Physics
Denis Tihon, Stafford Withington, Christopher N Thomas, Christophe Craeye
In many applications of absorbing structures it is important to understand their spatial response to incident fields, for example in thermal solar panels, bolometric imaging, and controlling radiative heat transfer. In practice, the illuminating field often originates from thermal sources and is only partially spatially coherent when it reaches the absorbing device. In this paper, we present a method to fully characterize the way a structure can absorb such partially coherent fields. The method is presented for any three-dimensional material and accounts for the partial coherence and partial polarization of the incident light...
December 1, 2016: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Chunyu Liu, Zhiqi Li, Zhihui Zhang, Xinyuan Zhang, Liang Shen, Wenbin Guo, Liu Zhang, Yongbing Long, Shengping Ruan
Tetrafluoro-tetracyanoquinodimethane (F4-TCNQ), a strong molecular acceptor, has been proved to be an excellent candidate to achieve the p-type doping effect. When F4-TCNQ is incorporated into a poly(3-hexylthiophene) (P3HT): indene-C60 bisadduct (ICBA) active layer, superior behavior upon inducing polymer donor excited electron transport is demonstrated due to the addition of a deep-lying lowest unoccupied molecular orbital (LUMO) from F4-TCNQ, leading to the realization of organic solar cells (OSCs) with an improved power conversion efficiency (PCE) of 5...
November 30, 2016: Physical Chemistry Chemical Physics: PCCP
N Katsoulas, D Antoniadis, I L Tsirogiannis, E Labraki, T Bartzanas, C Kittas
The objectives of this effort was to study the effect of vertical (green wall) and horizontal (pergola) green structures on the microclimate conditions of the building surroundings and estimate the thermal perception and heat stress conditions near the two structures. The experimental data were used to validate the results simulated by the recent version (V4.0 preview III) of ENVI-met software which was used to simulate the effect of different design parameters of a pergola and a green façade on microclimate and heat stress conditions...
November 29, 2016: International Journal of Biometeorology
Ching-Chuan Wei, Yu-Chang Song, Chia-Chi Chang, Chuan-Bi Lin
Solar energy is certainly an energy source worth exploring and utilizing because of the environmental protection it offers. However, the conversion efficiency of solar energy is still low. If the photovoltaic panel perpendicularly tracks the sun, the solar energy conversion efficiency will be improved. In this article, we propose an innovative method to track the sun using an image sensor. In our method, it is logical to assume the points of the brightest region in the sky image representing the location of the sun...
November 25, 2016: Sensors
Guo-Jun Kang, Chao Song, Xue-Feng Ren
The electronic geometries and optical properties of two D-π-A type zinc porphyrin dyes (NCH₃-YD2 and TPhe-YD) were systematically investigated by density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to reveal the origin of significantly altered charge transfer enhancement by changing the electron donor of the famous porphyrin-based sensitizer YD2-o-C8. The molecular geometries and photophysical properties of dyes before and after binding to the TiO₂ cluster were fully investigated...
November 25, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Weifu Sun, Zihan Chen, Junli Zhou, Dongyu Li, Zhen Huang, Xiao Jin, Qin Zhang, Feng Li, Qinghua Li
In this work, ytterbium-erbium co-doped strontium molybdate (SrMoO4, SMO) nanophosphors (NPs), denoted as SMO:Yb/Er, have been successfully prepared. These NPs were then incorporated into TiO2 acceptor films in hybrid solar cells to enhance light harvesting by virtue of an up-conversion process where low energy photons can be converted into high energy photons through multi-photon processes. The results showed that the SMO:Yb/Er single crystal NPs are capable of turning near infrared photons into visible ones that can be easily captured by poly(thieno[3,4-b]-thiophene/benzodithiophene) (PTB7)...
November 29, 2016: Physical Chemistry Chemical Physics: PCCP
Li Jun Fang, Xue Lu Wang, Jun Jie Zhao, Yu Hang Li, Yu Lei Wang, Xu Lei Du, Zhi Fei He, Hui Dan Zeng, Hua Gui Yang
Porous oxygen-doped graphitic carbon nitride (g-C3N4) with feeble nitrogen vacancies was fabricated through thermal polycondensation of melamine with an appropriate amount of polyvinylpyrrolidone. After optimization, the bandgap of g-C3N4 can be narrowed by 0.2 eV and the specific surface area expanded, which contribute to increasing the utilization of solar energy. Consequently, the optimized g-C3N4 exhibits impressive enhancement in photocatalytic hydrogen evolution performance, by nearly 5 times compared with the pristine one under the irradiation of visible light...
November 29, 2016: Chemical Communications: Chem Comm
Katherine Georgina Meacham, Xavier Sirault, W Paul Quick, Susanne von Caemmerer, Robert T Furbank
Genetic improvement of photosynthetic performance of cereal crops and increasing the efficiency with which solar radiation is converted into biomass has recently become a major focus for crop physiologists and breeders. The pulse amplitude modulated chlorophyll fluorescence technique (PAM) allows quantitative leaf level monitoring of the utilization of energy for photochemical light conversion and photo-protection in natural environments, potentially over the entire crop lifecycle. Here the diurnal relationship between electron transport rate (ETR) and irradiance was measured in five cultivars of Oryza sativa in canopy conditions with PAM fluorescence under natural solar radiation...
November 28, 2016: Plant Physiology
Ramesh Ghosh, P K Giri
Semiconductor nanowires (NWs), in particular Si NWs, have attracted much attention in the last decade for their unique electronic properties and potential applications in several emerging areas. With the introduction of heterostructures (HSs) on NWs, new functionalities are obtained and the device performance is improved significantly in many cases. Due to the easy fabrication techniques, excellent optoelectronic properties and compatibility of forming HSs with different inorganic/organic materials, Si NW HSs have been utilized in various configurations and device architectures...
November 28, 2016: Nanotechnology
Zhong Zheng, Omar M Awartani, Bhoj Gautam, Delong Liu, Yunpeng Qin, Wanning Li, Alexander Bataller, Kenan Gundogdu, Harald Ade, Jianhui Hou
Fullerene-free organic solar cells show over 11% power conversion efficiency, processed by low toxic solvents. The applied donor and acceptor in the bulk heterojunction exhibit almost the same highest occupied molecular orbital level, yet exhibit very efficient charge creation.
November 28, 2016: Advanced Materials
Chunhui Duan, Germán Zango, Miguel García Iglesias, Fallon J M Colberts, Martijn M Wienk, M Victoria Martínez-Díaz, René A J Janssen, Tomás Torres
Four hexachlorosubphthalocyanines SubPcCl6 -X bearing different axial substituents (X) have been synthesized for use as novel electron acceptors in solution-processed bulk-heterojunction organic solar cells. Subphthalocyanines are aromatic chromophoric molecules with cone-shaped structure, good solution processability, intense optical absorption in the visible spectral region, appropriate electron mobilities, and tunable energy levels. Solar cells with subphthalocyanines as the electron acceptor and PTB7-Th as the electron donor exhibit a power conversion efficiency up to 4 % and an external quantum efficiency approaching 60 % due to significant contributions from both the electron donor and the electron acceptor to the photocurrent, indicating a promising prospect of non-fullerene acceptors based on subphthalocyanines and structurally related systems...
November 28, 2016: Angewandte Chemie
Bruno S Leite, Cristiano C Bastos, Antonio C Pavão
The infrared spectrum of water observed in sunspots is complex and dense, with bands separated by approximately 0.01 cm(-1). For top asymmetrical molecules, there is no theoretical approach that allows for the calculation of rotovibrational energy with such precision. Experimentally derived rotovibracional energy levels of water at high temperatures combined with variational calculations have been used for the band assignments. These energy levels are employed to refine the analysis of a small portion of the infrared absorption spectrum...
December 2016: Journal of Molecular Modeling
Alexandre Cameron, Alexandros Alexakis
At the heart of today's solar magnetic field evolution models lies the alpha dynamo description. In this work, we investigate the fate of alpha dynamos as the magnetic Reynolds number Rm is increased. Using Floquet theory, we are able to precisely quantify mean-field effects like the alpha and beta effect (i) by rigorously distinguishing dynamo modes that involve large-scale components from the ones that only involve small scales, and by (ii) providing a way to investigate arbitrary large-scale separations with minimal computational cost...
November 11, 2016: Physical Review Letters
E Tenuta, C Zheng, O Rubel
Degradation of hybrid halide perovskites under the influence of environmental factors impairs future prospects of using these materials as absorbers in solar cells. First principle calculations can be used as a guideline in search of new materials, provided we can rely on their predictive capabilities. We show that the instability of perovskites can be captured using ab initio total energy calculations for reactants and products augmented with additional thermodynamic data to account for finite temperature effects...
November 24, 2016: Scientific Reports
Cindy G Tang, Mervin C Y Ang, Kim-Kian Choo, Venu Keerthi, Jun-Kai Tan, Mazlan Nur Syafiqah, Thomas Kugler, Jeremy H Burroughes, Rui-Qi Png, Lay-Lay Chua, Peter K H Ho
To make high-performance semiconductor devices, a good ohmic contact between the electrode and the semiconductor layer is required to inject the maximum current density across the contact. Achieving ohmic contacts requires electrodes with high and low work functions to inject holes and electrons respectively, where the work function is the minimum energy required to remove an electron from the Fermi level of the electrode to the vacuum level. However, it is challenging to produce electrically conducting films with sufficiently high or low work functions, especially for solution-processed semiconductor devices...
November 23, 2016: Nature
C Rodman, G Almeida-Porada, S George, J Moon, S Soker, T Pardee, M Beaty, P Guida, S P Sajuthi, C D Langefeld, S J Walker, P F Wilson, C D Porada
Future deep space missions to Mars and near-Earth asteroids will expose astronauts to chronic solar energetic particles (SEP) and galactic cosmic ray (GCR) radiation, and likely one or more solar particle events (SPEs). Given the inherent radiosensitivity of hematopoietic cells and short latency period of leukemias, space radiation-induced hematopoietic damage poses a particular threat to astronauts on extended missions. We show that exposing human hematopoietic stem/progenitor cells (HSC) to extended mission-relevant doses of accelerated high-energy protons and iron ions: 1) introduces mutations that are frequently located within genes involved in hematopoiesis and are distinct from those induced by γ-radiation; 2) dramatically reduces in vitro colony-formation; 3) markedly alters engraftment and lineage commitment in vivo; and 4) leads to the development, in vivo, of what appears to be T-ALL...
November 24, 2016: Leukemia: Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K
Ashwith Chilvery, Sanjib Das, Padmaja Guggilla, Christina Brantley, Anderson Sunda-Meya
Perovskite solar cells (PSCs) were developed in 2009 and have led to a number of significant improvements in clean energy technology. The power conversion efficiency (PCE) of PSCs has increased exponentially and currently stands at 22%. PSCs are transforming photovoltaic (PV) technology, outpacing many established PV technologies through their versatility and roll-to-roll manufacturing compatibility. The viability of low-temperature and solution-processed manufacturing has further improved their viability. This article provides a brief overview of the stoichiometry of perovskite materials, the engineering behind various modes of manufacturing by solution processing methods, and recommendations for future research to achieve large-scale manufacturing of high efficiency PSCs...
2016: Science and Technology of Advanced Materials
Gillian Collins, Eileen Armstrong, David McNulty, Sally O'Hanlon, Hugh Geaney, Colm O'Dwyer
This perspective reviews recent advances in inverse opal structures, how they have been developed, studied and applied as catalysts, catalyst support materials, as electrode materials for batteries, water splitting applications, solar-to-fuel conversion and electrochromics, and finally as photonic photocatalysts and photoelectrocatalysts. Throughout, we detail some of the salient optical characteristics that underpin recent results and form the basis for light-matter interactions that span electrochemical energy conversion systems as well as photocatalytic systems...
2016: Science and Technology of Advanced Materials
Varun Vohra, Takuya Anzai, Shusei Inaba, William Porzio, Luisa Barba
Polymer solar cells (PSCs) are greatly influenced by both the vertical concentration gradient in the active layer and the quality of the various interfaces. To achieve vertical concentration gradients in inverted PSCs, a sequential deposition approach is necessary. However, a direct approach to sequential deposition by spin-coating results in partial dissolution of the underlying layers which decreases the control over the process and results in not well-defined interfaces. Here, we demonstrate that by using a transfer-printing process based on polydimethylsiloxane (PDMS) stamps we can obtain increased control over the thickness of the various layers while at the same time increasing the quality of the interfaces and the overall concentration gradient within the active layer of PSCs prepared in air...
2016: Science and Technology of Advanced Materials
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