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M Välimäki, E Jansson, P Korhonen, A Peltoniemi, S Rousu
Freedom of design that was introduced as organic photovoltaic (OPV) modules were fabricated by printing. As proof-of-concept, we show OPV leaf fabrication in A5 size using gravure and rotary screen printing processes for the main active layers of the OPV structure. These printing methods allow direct printing of any kind of arbitrary, two-dimensional shapes including patterning of the electric contacts thus post-patterning stages are not needed. Fabrication of custom-shaped OPV modules requires detailed information about the technical boundaries set by the manufacturing process and materials which in turn influence the layout design and R2R upscaling...
December 2017: Nanoscale Research Letters
Joseph L Garrett, Elizabeth M Tennyson, Miao Hu, Jinsong Huang, Jeremy N Munday, Marina S Leite
Hybrid organic-inorganic perovskites based on methylammonium lead iodide (MAPbI3) are an emerging material with great potential for high-performance and low-cost photovoltaics. However, for perovskites to become a competitive and reliable solar cell technology, their instability and spatial variation must be understood and controlled. While the macroscopic characterization of the devices as a function of time is very informative, a nanoscale identification of their real-time local optoelectronic response is still missing...
February 22, 2017: Nano Letters
Feng Li, Hong Wang, Dominik Kufer, Liangliang Liang, Weili Yu, Erkki Alarousu, Chun Ma, Yangyang Li, Zhixiong Liu, Changxu Liu, Nini Wei, Fei Wang, Lang Chen, Omar F Mohammed, Andrea Fratalocchi, Xiaogang Liu, Gerasimos Konstantatos, Tom Wu
Organolead trihalide perovskites have drawn substantial interest for photovoltaic and optoelectronic applications due to their remarkable physical properties and low processing cost. However, perovskite thin films suffer from low carrier mobility as a result of their structural imperfections such as grain boundaries and pinholes, limiting their device performance and application potential. Here we demonstrate a simple and straightforward synthetic strategy based on coupling perovskite films with embedded single-walled carbon nanotubes...
February 22, 2017: Advanced Materials
Fuzhi Huang, Alexander R Pascoe, Wu-Qiang Wu, Zhiliang Ku, Yong Peng, Jie Zhong, Rachel A Caruso, Yi-Bing Cheng
The efficiencies of the hybrid organic-inorganic perovskite solar cells have been rapidly approaching the benchmarks held by the leading thin-film photovoltaic technologies. Arguably, one of the most important factors leading to this rapid advancement is the ability to manipulate the microstructure of the perovskite layer and the adjacent functional layers within the device. Here, an analysis of the nucleation and growth models relevant to the formation of perovskite films is provided, along with the effect of the perovskite microstructure (grain sizes and voids) on device performance...
February 22, 2017: Advanced Materials
K Galkowski, A A Mitioglu, A Surrente, Z Yang, D K Maude, P Kossacki, G E Eperon, J T-W Wang, H J Snaith, P Plochocka, R J Nicholas
The family of organic-inorganic tri-halide perovskites including MA (MethylAmmonium)PbI3, MAPbI3-xClx, FA (FormAmidinium)PbI3 and FAPbBr3 are having a tremendous impact on the field of photovoltaic cells due to the combination of their ease of deposition and high energy conversion efficiencies. Device performance, however, is known to be still significantly affected by the presence of inhomogeneities. Here we report on a study of temperature dependent micro-photoluminescence which shows a strong spatial inhomogeneity related to the presence of microcrystalline grains, which can be both bright and dark...
February 22, 2017: Nanoscale
Xu Lin, Mika Suzuki, Marina Gushiken, Mitsuaki Yamauchi, Takashi Karatsu, Takahiro Kizaki, Yuki Tani, Ken-Ichi Nakayama, Mitsuharu Suzuki, Hiroko Yamada, Takashi Kajitani, Takanori Fukushima, Yoshihiro Kikkawa, Shiki Yagai
The design of molecular systems with high-fidelity self-assembly pathways that include several levels of hierarchy is of primary importance for the understanding of structure-function relationships, as well as for controlling the functionality of organic materials. Reported herein is a high-fidelity self-assembly system that comprises two hydrogen-bonding molecular semiconductors with regioisomerically attached short alkyl chains. Despite the availability of both discrete cyclic and polymeric linear hydrogen-bonding motifs, the two regioisomers select one of the two motifs in homogeneous solution as well as at the 2D-confined liquid-solid interface...
February 22, 2017: Scientific Reports
Tao Zhang, Deng-Ke Wang, Nan Jiang, Zheng-Hong Lu
Tandem device is an important architecture in fabricating high performance organic light-emitting diodes and organic photovoltaic cells. The key element in making a high performance tandem device is the connecting materials stack, which plays an important role in electric field distribution, charge generation and charge injection. For a tandem organic light-emitting diode (OLED) with a simple Liq/Al/MoO3 stack, we discovered that there is a significant current lateral spreading causing light emission over an extremely large area outside the OLED pixel when the Al thickness exceeds 2 nm...
February 22, 2017: Scientific Reports
Xiaofang Cheng, Liqiang Huang, Lifu Zhang, Qingyun Ai, Lie Chen, Yiwang Chen
Self-assembled small-molecules (SASMs) are of effective materials to improve the interfacial issues between the metal/metal oxide and the overlying organic layer. In this work, surface modification of indium tin oxide (ITO) electrode through a series of Cl-contained SASMs has been exploited to control the surface properties of ITO and device performance in organic photovoltaics. Depending on the position and degrees of chlorination for SASMs, we could precisely manipulate the work function of the ITO electrode, and chemisorption of SASMs on ITO as well...
February 22, 2017: ACS Applied Materials & Interfaces
Xiaofu Wu, Zijian Zhang, Hao Hang, Yonghong Chen, Yuxiang Xu, Hui Tong, Lixiang Wang
The development of photovoltaic polymers based on C3h -symmetric benzotrithiophene (C3h -BTT), an analogue of the well-known benzodithiophene (BDT) donor unit, has been severely limited due to difficult processability. Here the authors report the preparation of solution-processable C3h -BTT-based hyperbranched conjugated polymer nanoparticles (BTT-HCPNs) with tunable particle sizes via Stille miniemulsion polymerization. Compared with the corresponding star-shaped small molecule (C3h -BTT core with three diketopyrrolopyrrole arms, BTT-3DPP) with a wide bandgap (1...
February 21, 2017: Macromolecular Rapid Communications
Huimin Jia, Beibei Zhang, Weiwei He, Yong Xiang, Zhi Zheng
The rational design of high performance hetero-structure photovoltaic devices requires a full understanding of the photoinduced charge transfer mechanism and kinetics at the interface of heterojunctions. In this paper, we intelligently fabricated p-BiOBr/n-CdS heterojunctions with perfect nanosheet arrays by using a facile successive ionic layer adsorption and reaction and chemical bath deposition methods at low temperature. A BiOBr/CdS heterojunction based solar cell has been fabricated which exhibited enhanced photovoltaic responses...
February 21, 2017: Nanoscale
Yanjun Fang, Haotong Wei, Qingfeng Dong, Jinsong Huang
Photon recycling, that is, iterative self-absorption and re-emission by the photoactive layer itself, has been speculated to contribute to the high open-circuit voltage in several types of high efficiency solar cells. For organic-inorganic halide perovskites that have yielded highly efficient photovoltaic devices, however, it remains unclear whether the photon recycling effect is significant enough to improve solar cell efficiency. Here we quantitatively evaluate the re-absorption and re-emission processes to determine photon recycling efficiency in hybrid perovskite with its single crystals by measuring the ratio of the re-emitted photons to the initially excited photons, which is realized by modulating their polarization to differentiate them...
February 21, 2017: Nature Communications
Jacob B Khurgin
Noble metals that currently dominate the fields of plasmonics and metamaterials suffer from large ohmic losses. Some of the new plasmonic materials, such as doped oxides and nitrides, have smaller material loss, and using them in place of metals carries the promise of reduced-loss plasmonic and metamaterial structures, with sharper resonances and higher field concentrations. This promise is put to a rigorous analytical test in this work, which reveals that having low material loss is not sufficient to have reduced modal loss in plasmonic structures...
March 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Ting Liao, Ziqi Sun, Shi Xue Dou
Low solar energy harvesting and conversion efficiency has become a major problem in solar energy science and engineering owing to the difficulty in capturing solar energy across the wide solar spectrum, especially in the visible light range. Inspired by the extraordinary properties of materials arising from decreased dimensions, in this study, we explore a nano-contact system formed by a two-dimensional (2D) TiO2 monolayer and II-VI semiconductor (CdX)13 (X = S, Se and Te) nanocages for engineering the visible light absorption...
February 20, 2017: ACS Applied Materials & Interfaces
Benoit Gaury, Paul M Haney
Analytic expressions are presented for the dark current-voltage relation J(V ) of a pn(+) junction with positively charged columnar grain boundaries with high defect density. These expressions apply to non-depleted grains with sufficiently high bulk hole mobilities. The accuracy of the formulas is verified by direct comparison to numerical simulations. Numerical simulations further show that the dark J(V ) can be used to determine the open-circuit potential Voc of an illuminated junction for a given short-circuit current density Jsc...
December 21, 2016: Journal of Applied Physics
Ming-Min Yang, Akash Bhatnagar, Zheng-Dong Luo, Marin Alexe
Domain walls, which are intrinsically two dimensional nano-objects exhibiting nontrivial electronic and magnetic behaviours, have been proven to play a crucial role in photovoltaic properties of ferroelectrics. Despite this recognition, the electronic properties of domain walls under illumination until now have been accessible only to macroscopic studies and their effects upon the conduction of photovoltaic current still remain elusive. The lack of understanding hinders the developing of nanoscale devices based on ferroelectric domain walls...
February 20, 2017: Scientific Reports
Pawan Kumar, Satbir Singh, V N Singh, Nidhi Singh, R K Gupta, Bipin Kumar Gupta
A novel method for demonstration of photoluminescence intensity distribution in upconverting nanorod bundles using confocal microscopy is reported. Herein, a strategy for the synthesis of highly luminescent dual mode upconverting/downshift Y1.94O3:Ho(3+)0.02/Yb(3+)0.04 nanorod bundles by a facile hydrothermal route has been introduced. These luminescent nanorod bundles exhibit strong green emission at 549 nm upon excitations at 449 nm and 980 nm with quantum efficiencies of ~6.3% and ~1.1%, respectively...
February 13, 2017: Scientific Reports
Longzhen You, Bin Liu, Tao Liu, Bingbing Fan, Yunhao Cai, Lin Guo, Yanming Sun
Tungsten oxide as an alternative to conventional acidic PEDOT:PSS has attracted much attention in organic solar cells (OSCs). However, the vacuum-processed WO3 layer and high temperature sol-gel hydrolyzed WOX are incompatible with large-scale manufacturing of OSCs. Here, we report for the first time that a specific tungsten oxide WO2.72 (W18O49) nanowire can function well as the anode buffer layer. The nw-WO2.72 film exhibits a high optical transparency. The power conversion efficiency (PCE) of OSCs based on three typical polymer active layers PTB7:PC71BM, PTB7-Th:PC71BM, and PDBT-T1:PC71BM with nw-WO2...
February 17, 2017: ACS Applied Materials & Interfaces
Özgül Birel, Said Nadeem, Hakan Duman
The current review aims to collect short information about photovoltaic performance and structure of porphyrin-based sensitizers used in dye-sensitized solar cells (DSSC). Sensitizer is the key component of the DSSC device. Structure of sensitizer is important to achieve high photovoltaic performance. Porphyrin derivatives are suitable for DSSC applications due to their thermal, electronic and photovoltaic properties. It describes some electrochemical and spectral properties as well as thestructure of porphyrin dyes used in dye based-solar cells...
February 16, 2017: Journal of Fluorescence
Sebastian Engmann, Hyun Wook Ro, Andrew Herzing, Chad R Snyder, Lee J Richter, Paul B Geraghty, David J Jones
Solution-processable small molecule photovoltaics based on the novel molecular donor, benzodithiophene terthiophene rhodanine (BTR), recently have shown maximum power conversion efficiencies above 8 % for active layer thicknesses up to 400 nm, using post process solvent vapor annealing (SVA) with tetrahydrofuran (THF). Here we report an in-situ study on the morphology evolution during SVA using the moderate solvent THF and the good solvent chloroform (CF). The combination of real-time grazing incidence X-ray diffraction (GIXD) and grazing incidence small angle X-ray scattering (GISAXS) allows us to draw a complete picture of the evolution of crystallinity and phase purity during post process annealing...
October 28, 2016: Journal of Materials Chemistry. A, Materials for Energy and Sustainability
Andrii Iurov, Godfrey Gumbs, Danhong Huang
We have numerically calculated electron exchange and correlation energies and dynamical polarization functions for recently discovered silicene, germanene and other buckled honeycomb lattices at various temperatures. We have compared the dependence of these energies on the chemical potential, field-induced gap and temperature and we have concluded that in many cases they behave qualitatively in a similar way, i.e. increasing with the doping, decreasing significantly at elevated temperatures, and displaying different dependences on the asymmetry gap at various temperatures...
February 16, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
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