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Ying Yu, Xing Li, Zhongjin Shen, Xiaoyu Zhang, Peng Liu, Yuting Gao, Tao Jiang, Jianli Hua
In this work, we reported two new quinoxaline-based sensitizers (BQI and BQII) for p-type dye-sensitized solar cells (p-DSSCs) featuring carboxylic acid and pyridine as anchoring groups, respectively, in combination with triphenylamine donor. The optical, electrochemical and photovoltaic properties of BQI and BQII were investigated. Results showed that BQI-based p-DSSC with carboxylic acid anchoring group obtained higher photoelectric conversion efficiency (PCE) of 0.140%. To further optimize the device performance, we added a layer of TiO2 on the surface of NiO film as a barrier layer, which contributed to the improvement of the photocurrent density from 3...
November 10, 2016: Journal of Colloid and Interface Science
Ibrahim M A Mohamed, Van-Duong Dao, Ahmed S Yasin, Ho-Suk Choi, KhalilAbdelrazek Khalil, Nasser A M Barakat
Chemical doping is a widely-used strategy to improve the performance of TiO2 for the dye-sensitized solar cells (DSCs). However, the effect of two efficient dopants has been rarely investigated. We present the synthesis of GO@SnO2/TiO2 nanofibers (NFs) by a facile method using electrospinning and hydrothermal processes. The synthesized NFs are described in terms of morphology, crystallinity and chemistry through FESEM, TEM, HR-TEM, XRD, EDX, XPS, FT-IR and Raman spectra. As the results, the axial ratio and the average diameter of NFs decreased after the hydrothermal treatment and calcination process, respectively...
November 12, 2016: Journal of Colloid and Interface Science
Qiyi Zhao, Yaohui Guo, Yixuan Zhou, Xianding Yan, Xinlong Xu
MoS2 based photoelectrodes with different thickness have been fabricated by liquid phase exfoliation and vacuum filtration method. Absorption spectra clearly demonstrated two splitting absorption peaks due to the spin-orbit coupling and first principle calculation also indicate the spin-orbit coupling effect. These results combined with the SEM and TEM measurement suggests that the randomly stacked MoS2 films can maintain the properties of few-layered materials with good quality. As a proof-of-principle applications, photoelectrochemical experiments of MoS2 based photoelectrodes manifests that these MoS2 films are one kind of reversible and stable optoelectronic materials with tunable microampere photocurrent as the change of film thickness...
November 16, 2016: Journal of Colloid and Interface Science
Hiroaki Ishizuka, Tomoya Hayata, Masahito Ueda, Naoto Nagaosa
The photovoltaic effect due to the adiabatic quantum phase in noncentrosymmetric Weyl semimetals is studied. We particularly focus on the case in which an external ac electric field is applied. By considering a generalized Weyl Hamiltonian with nonlinear terms, we show that the photocurrent is induced by circularly, rather than linearly, polarized light. This photovoltaic current can be understood as an emergent electromagnetic induction in momentum space; the Weyl node is a magnetic monopole in momentum space, the circular motion of which induces the electric field...
November 18, 2016: Physical Review Letters
Janina Wirth, Kory K Green, Megan O'Connor, Shuang F Lim
Upconverting nanoparticles show potential applications in the field of photovoltaics and array-based detection devices. While fluorescence enhancement using interference of incident radiation is well known in Stokes-shift type systems such as fluorescent dyes; the effect of such interference geometry in nonlinear Anti-Stokes type emission, such as in upconversion rare earth photophysics is demonstrated for the first time. This work describes in detail the influence of the interference modulation on both the excitation (interion energy transfer) and radiative decay with nonradiative decay processes active between emissive levels...
December 2, 2016: Small
Katherine T Fountaine, Hans Joachim Lewerenz, Harry A Atwater
Theoretical limiting efficiencies have a critical role in determining technological viability and expectations for device prototypes, as evidenced by the photovoltaics community's focus on detailed balance. However, due to their multicomponent nature, photoelectrochemical devices do not have an equivalent analogue to detailed balance, and reported theoretical efficiency limits vary depending on the assumptions made. Here we introduce a unified framework for photoelectrochemical device performance through which all previous limiting efficiencies can be understood and contextualized...
December 2, 2016: Nature Communications
Tao Liu, Xuexue Pan, Xiangyi Meng, Yu Liu, Donghui Wei, Wei Ma, Lijun Huo, Xiaobo Sun, Tack Ho Lee, Minjuan Huang, Hyosung Choi, Jin Young Kim, Wallace C H Choy, Yanming Sun
A series of wide-bandgap (WBG) copolymers with different alkyl side chains are synthesized. Among them, copolymer PBT1-EH with moderatly bulky side chains on the acceptor unit shows the best photovoltaic performance with power conversion efficiency over 10%. The results suggest that the alkyl side-chain engineering is an effective strategy to further tuning the optoelectronic properties of WBG copolymers.
December 1, 2016: Advanced Materials
J H Du, H Jin, Z K Zhang, D D Zhang, S Jia, L P Ma, W C Ren, H M Cheng, P L Burn
The large surface roughness, low work function and high cost of transparent electrodes using multilayer graphene films can limit their application in organic photovoltaic (OPV) cells. Here, we develop single layer graphene (SLG) films as transparent anodes for OPV cells that contain light-absorbing layers comprised of the evaporable molecular organic semiconductor materials, zinc phthalocyanine (ZnPc)/fullerene (C60), as well as a molybdenum oxide (MoOx) interfacial layer. In addition to an increase in the optical transmittance, the SLG anodes had a significant decrease in surface roughness compared to two and four layer graphene (TLG and FLG) anodes fabricated by multiple transfer and stacking of SLGs...
December 1, 2016: Nanoscale
Luca La Notte, Enrica Villari, Alessandro Lorenzo Palma, Alberto Sacchetti, Maria Michela Giangregorio, Giovanni Bruno, Aldo Di Carlo, Giuseppe Valerio Bianco, Andrea Reale
A five-layer (5L) graphene on a glass substrate has been demonstrated as a transparent conductive electrode to replace indium tin oxide (ITO) in organic photovoltaic devices. The required low sheet resistance, while maintaining high transparency, and the need of a wettable surface are the main issues. To overcome these, two strategies have been applied: (i) the p-doping of the multilayer graphene, thus reaching 25 Ω □(-1) or (ii) the O2-plasma oxidation of the last layer of the 5L graphene that results in a contact angle of 58° and a sheet resistance of 134 Ω □(-1)...
December 1, 2016: Nanoscale
Swe Zin Oo, Martin D B Charlton
Recently, a comprehensive three dimensional computational model based on rigorous coupled wave analysis (RCWA) has been developed to investigate the properties of surface plasmons resident on metal coated arrays of inverted pyramidal pits used for SERS sensing applications in the form of 'klarite'. This simulation tool allows the identification of a variety of dispersive features including propagating and localized surface plasmons as well as simple diffraction relating to the influence of geometrical features...
November 28, 2016: Optics Express
Markus Leidinger, Christoph S Werner, Wataru Yoshiki, Karsten Buse, Ingo Breunig
Whispering-gallery resonators made of undoped and MgO-doped congruently grown lithium niobate are used to study electro-optic refractive index changes. Hereby, we focus on the volume photovoltaic and the pyroelectric effect, both providing an electric field driving the electro-optic effect. Our findings indicate that the light-induced photorefractive effect, combining the photovoltaic and electro-optic effect, is present only in the non-MgO-doped lithium niobate for exposure with light having wavelengths of up to 850 nm...
December 1, 2016: Optics Letters
Jefferson Dixon, Aravindh Rajan, Steven Bohlemann, Dusan Coso, Ajay D Upadhyaya, Ajeet Rohatgi, Steven Chu, Arun Majumdar, Shannon Yee
Betavoltaic energy converters (i.e., β-batteries) are attractive power sources because of their potential for high energy densities (>200 MWh/kg) and long duration continuous discharge (>1 year). However, conversion efficiencies have been historically low (<3%). High efficiency devices can be achieved by matching β-radiation transport length scales with the device physics length scales. In this work, the efficiency of c-Si devices using high-energy (>1 MeV) electrons emitted from (90)Sr as a power source is investigated...
December 1, 2016: Scientific Reports
Haijun Bin, Liang Gao, Zhi-Guo Zhang, Yankang Yang, Yindong Zhang, Chunfeng Zhang, Shanshan Chen, Lingwei Xue, Changduk Yang, Min Xiao, Yongfang Li
Simutaneously high open circuit voltage and high short circuit current density is a big challenge for achieving high efficiency polymer solar cells due to the excitonic nature of organic semdonductors. Herein, we developed a trialkylsilyl substituted 2D-conjugated polymer with the highest occupied molecular orbital level down-shifted by Si-C bond interaction. The polymer solar cells obtained by pairing this polymer with a non-fullerene acceptor demonstrated a high power conversion efficiency of 11.41% with both high open circuit voltage of 0...
December 1, 2016: Nature Communications
Jin Chang, Yuhei Ogomi, Chao Ding, Yao Hong Zhang, Taro Toyoda, Shuzi Hayase, Kenji Katayama, Qing Shen
The surface chemistry of colloidal quantum dots (QDs) plays an important role in determining the photoelectric properties of QD films and the corresponding quantum dot heterojunction solar cells (QDHSCs). To investigate the effects of the ligand structure on the photovoltaic performance and exciton dynamics of QDHSCs, PbS QDHSCs were fabricated by the solid state ligand exchange method with mercaptoalkanoic acid as the cross-linking ligand. Temperature-dependent photoluminescence and ultrafast transient absorption spectra show that the electronic coupling and charge transfer rate within QD ensembles were monotonically enhanced as the ligand length decreased...
November 30, 2016: Physical Chemistry Chemical Physics: PCCP
Yongming Zhao, Yurun Sun, Yang He, Shuzhen Yu, Jianrong Dong
A six-volt vertically-stacked, high current GaAs photovoltaic power converter (PPC) has been designed and fabricated to produce output power over 1 W under monochromatic illumination. An N(++)-GaAs/P(++)-AlGaAs tunnel junctions (TJs) structure has been used for connecting each sub-cell in this vertically-stacked PPC device. The thickness of the each GaAs sub-cell has been derived based on the calculation of absorption depth of photons with a wavelength of 808 nm using absorption coefficient obtained from ellipsometry measurements...
November 30, 2016: Scientific Reports
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
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
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
Sudipta Seth, Anunay Samanta
A facile and highly reproducible room temperature, open atmosphere synthesis of cesium lead halide perovskite nanocrystals of six different morphologies is reported just by varying the solvent, ligand and reaction time. Sequential evolution of the quantum dots, nanoplates and nanobars in one medium and nanocubes, nanorods and nanowires in another medium is demonstrated. These perovskite nanoparticles are shown to be of excellent crystalline quality with high fluorescence quantum yield. A mechanism of the formation of nanoparticles of different shapes and sizes is proposed...
November 25, 2016: Scientific Reports
Kyohei Nakano, Keisuke Tajima
Recent progress regarding planar heterojunctions (PHJs) is reviewed, with respect to the fundamental understanding of the photophysical processes at the donor/acceptor interfaces in organic photovoltaic devices (OPVs). The current state of OPV research is summarized and the advantages of PHJs as models for exploring the relationship between organic interfaces and device characteristics described. The preparation methods and the characterization of PHJ structures to provide key points for the appropriate handling of PHJs...
November 25, 2016: Advanced Materials
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