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https://www.readbyqxmd.com/read/28548495/pressure-induced-effects-in-organic-inorganic-hybrid-perovskites
#1
Paolo Postorino, Lorenzo Malavasi
In this perspective it is provided an overview of the pressure-induced effects on hybrid organic-inorganic perovskite for photovoltaics applications. It is shown that a fine-tuning of the most relevant photovoltaic properties, including band gap and carrier lifetime, is indeed possible by applying pressure over a rather small range and that such phenomena closely correlate with pressure-induced structural changes. High-pressure research can be used to search for new materials since the high-pressure structural configuration can be used as a model for tailoring ambient pressure compounds under proper chemical substitution, and the band-gap tuning and enhancement of carrier lifetime with applied pressures can be a guide to design new hybrid perovskites with desired optical properties as a function of structural parameters...
May 26, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28546887/energy-level-alignment-at-interfaces-between-manganese-phthalocyanine-and-c60
#2
Daniel Waas, Florian Rückerl, Martin Knupfer, Bernd Büchner
We have used photoelectron spectroscopy to determine the energy-level alignment at organic heterojunctions made of manganese phthalocyanine (MnPc) and the fullerene C60. We show that this energy-level alignment depends upon the preparation sequence, which is explained by different molecular orientations. Moreover, our results demonstrate that MnPc/C60 interfaces are hardly suited for application in organic photovoltaic devices, since the energy difference of the two lowest unoccupied molecular orbitals (LUMOs) is rather small...
2017: Beilstein Journal of Nanotechnology
https://www.readbyqxmd.com/read/28537311/naphthodifuran-based-zigzag-type-polycyclic-arene-with-conjugated-side-chains-for-efficient-photovoltaics
#3
Hongjian Peng, Xiangfeng Luan, Liuliu Feng, Jun Yuan, Zhi-Guo Zhang, Yongfang Li, Yingping Zou
Ladder-type conjugated structures with rigid and coplanar molecular frameworks feature longer effective conjugation, affirmative optoelectronic properties and strong intermolecular π-π interactions, which are ideal characteristics for organic photovoltaics. Here, a new "zigzag" angular-fused naphthodifuran (zNDF) based on alkoxyphenyl side chains was designed and synthesized. The distannylated zNDF building block was copolymerized with 4,7-di(5-bromothiophen-2-yl)-5,6-dioctyloxybenzo[c][1,2,5]thiadiazole and 5,8-bis(5-bromothiophen-2-yl)-2,3-bis(4-(2-ethylhexyloxy)-3-fluorophenyl)-6,7-difloroquinoxaline (Br-BT and Br-ffQx) acceptor units by Stille cross coupling reaction to form two new medium bandgap donor-acceptor polymers PzNDFP-BT and PzNDFP-ffQx, respectively...
May 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28537073/lead-free-mixed-tin-and-germanium-perovskites-for-photovoltaic-application
#4
Ming-Gang Ju, Jun Dai, Liang Ma, Xiao Cheng Zeng
The power conversion efficiency (PCE) of lead halide perov-skite photovoltaics has reached to 22.1% with significantly improved structural stability, thanks to the mixed cation and anion strategy. However, the mixing element strategy has not been widely seen in the design of lead-free perovskites for photovoltaic application. Herein, we report a comprehensive study of a series of lead-free and mixed tin and germanium halide perovskite materials. Most importantly, we predict that RbSn0.5Ge0.5I3 possesses not only a direct bandgap within the optimal range of 0...
May 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28536467/discrete-photoelectrodes-with-dyes-having-different-absorption-wavelengths-for-efficient-cobalt-based-tandem-dye-sensitised-solar-cells
#5
Phuong Ho, Suresh Thogiti, Yong Hui Lee, Jae Hong Kim
A pn-tandem dye-sensitised solar cell (pn-DSSC) employing a set of sensitisers with complementary absorption spectra and a less-corrosive cobalt-based electrolyte is presented. We applied three organic sensitisers (denoted C343, DCBZ, and SQ) featuring different absorption wavelengths for the p-DSSC, while keeping the n-DSSC sensitiser (denoted DCA10CN2) constant. Characterisation of the Co(+2/+3)-based DSSC devices revealed that SQ dye, with a longer absorption wavelength, showed broader spectra and increased photocurrent activity in the visible and near-infrared region compared to the other two devices with C343 and DCBZ in the pn-DSSCs...
May 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28535037/hybrid-doping-of-few-layer-graphene-via-a-combination-of-intercalation-and-surface-doping
#6
Ahmed E Mansour, Ahmad R Kirmani, Stephen Barlow, Seth R Marder, Aram Amassian
Surface molecular doping of graphene has been shown to modify its work function and increase its conductivity. However, the associated shifts in work function and increases in carrier concentration are highly coupled and limited by the surface coverage of dopant molecules on graphene. Here we show that few-layer graphene (FLG) can be doped using a hybrid approach, effectively combining surface doping by larger (metal-)organic molecules, while smaller molecules, such as Br2 and FeCl3, intercalate into the bulk...
May 23, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28534909/engineering-band-gap-and-electronic-transport-in-organic-inorganic-halide-perovskites-by-superlattices
#7
Rahul Singh, Ranjith Kottokkaran, Vikram L Dalal, Ganesh Balasubramanian
Organic/inorganic lead and tin halide perovskites (CH3NH3PbI3 and CH3NH3SnI3) have been promising for photovoltaics because of their high charge carrier mobility, and large absorption coefficient and diffusion length. Both these perovskites also have a notable Seebeck coefficient, depending on the doping level, indicating their potential as thermoelectrics. We create superlattices of these hybrid organic-inorganic halide perovskites and investigate electronic transport through them using first principles computations and experiments...
May 23, 2017: Nanoscale
https://www.readbyqxmd.com/read/28530404/role-of-crystallization-in-the-morphology-of-polymer-non-fullerene-acceptor-bulk-heterojunctions
#8
Kathryn A O'Hara, David P Ostrowski, Unsal Koldemir, Christopher J Takacs, Sean E Shaheen, Alan Sellinger, Michael L Chabinyc
Many high efficiency organic photovoltaics use fullerene-based acceptors despite their high production cost, weak optical absorption in the visible range, and limited synthetic variability of electronic and optical properties. To circumvent this deficiency, non-fullerene small-molecule acceptors have been developed that have good synthetic flexibility, allowing for precise tuning of optoelectronic properties, leading to enhanced absorption of the solar spectrum and increased open-circuit voltages (VOC). We examined the detailed morphology of bulk heterojunctions of poly(3-hexylthiophene) and the small-molecule acceptor HPI-BT to reveal structural changes that lead to improvements in the fill factor of solar cells upon thermal annealing...
May 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28530392/a-hexafluoroquinoxaline-based-polymer-for-nonfullerene-solar-cells-reaching-9-4-efficiency
#9
Shutao Xu, Liuliu Feng, Jun Yuan, Zhi-Guo Zhang, Yongfang Li, Hongjian Peng, Yingping Zou
hrough introducing six fluorine atoms onto quinoxaline (Qx), a new electron acceptor unit-hexafluoroquinoxaline (HFQx) is firstly synthesized. Based on this unit, we synthesize a new donor-acceptor (D-A) copolymer (HFQx-T), which is composed of benzodithiophene (BDT) derivative donor block and an HFQx accepting block. The strong electron-withdrawing properties of fluorine atoms increase significantly the voltage open-circuit (Voc) by tuning the highest occupied molecular orbital (HOMO) energy level. In addition, fluorine atoms enhance the absorption coefficient of the conjugated copolymer and change the film morphology, which implies an increase of the short-circuit current density (Jsc) and fill factor (FF)...
May 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28524245/towards-efficient-spectral-converters-through-materials-design-for-luminescent-solar-devices
#10
REVIEW
Barry McKenna, Rachel C Evans
Single-junction photovoltaic devices exhibit a bottleneck in their efficiency due to incomplete or inefficient harvesting of photons in the low- or high-energy regions of the solar spectrum. Spectral converters can be used to convert solar photons into energies that are more effectively captured by the photovoltaic device through a photoluminescence process. Here, recent advances in the fields of luminescent solar concentration, luminescent downshifting, and upconversion are discussed. The focus is specifically on the role that materials science has to play in overcoming barriers in the optical performance in all spectral converters and on their successful integration with both established (e...
May 19, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28520164/transition-metal-chalcogenides-graphene-ensembles-for-light-induced-energy-applications
#11
Antonia Kagkoura, Theodosis Skaltsas, Nikos Tagmatarchis
Recently, nanomaterials that harvest solar energy and convert it to other forms of energy are of great interest. In this context, transition metal chalcogenides (TMCs) are lately on the spotlight due to their optoelectronic properties that render them potential candidates mainly in energy conversion applications. Integration of TMCs onto a strong electron accepting material, such as graphene, yielding novel TMC/graphene ensembles is of high significance, since photoinduced charge-transfer phenomena leading to intra-ensemble charge-separation, may occur...
May 18, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28517016/graphene-as-an-electrode-for-solution-processed-electron-transporting-organic-transistors
#12
Subir Parui, Mário Ribeiro, Ainhoa Atxabal, Roger Llopis, Fèlix Casanova, Luis E Hueso
Organic field-effect transistors (OFETs) are fundamental building blocks for plastic electronics such as organic photovoltaics or bendable displays with organic light emitting diodes, and radio-frequency identification (RFID) tags. A key part in the performance of OFET is the organic material constituting the channel. OFETs based on solution-processed polymers represent a new class of organic electronic devices. Recent developments in upscale solution-processed polymers have advanced towards high throughput, low-cost, and environmentally friendly materials for high-performance applications...
May 18, 2017: Nanoscale
https://www.readbyqxmd.com/read/28508866/tuning-colloidal-quantum-dot-band-edge-positions-through-solution-phase-surface-chemistry-modification
#13
Daniel M Kroupa, Márton Vörös, Nicholas P Brawand, Brett W McNichols, Elisa M Miller, Jing Gu, Arthur J Nozik, Alan Sellinger, Giulia Galli, Matthew C Beard
Band edge positions of semiconductors determine their functionality in many optoelectronic applications such as photovoltaics, photoelectrochemical cells and light emitting diodes. Here we show that band edge positions of lead sulfide (PbS) colloidal semiconductor nanocrystals, specifically quantum dots (QDs), can be tuned over 2.0 eV through surface chemistry modification. We achieved this remarkable control through the development of simple, robust and scalable solution-phase ligand exchange methods, which completely replace native ligands with functionalized cinnamate ligands, allowing for well-defined, highly tunable chemical systems...
May 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/28508629/inorganic-ligand-thiosulfate-capped-quantum-dots-for-efficient-quantum-dot-sensitized-solar-cells
#14
Zhenwei Ren, Juan Yu, Zhenxiao Pan, Jizheng Wang, Xinhua Zhong
The insulating nature of organic ligands containing long hydrocarbon tails brings forward serious limitations for presynthesized quantum dots (QDs) in photovoltaic applications. Replacing the initial organic hydrocarbon chain ligands with simple, cheap, and small inorganic ligands is regarded as an efficient strategy for improving the performance of the resulting photovoltaic devices. Herein, thiosulfate (S2O3(2-)), and sulfide (S(2-)) were employed as ligand-exchange reagents to get access to the inorganic ligand S2O3(2-)- and S(2-)-capped CdSe QDs...
May 24, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28508587/organic-inorganic-hybrid-perovskite-with-controlled-dopant-modification-and-application-in-photovoltaic-device
#15
Wangen Zhao, Dong Yang, Shengzhong Frank Liu
Organic-inorganic hybrid perovskite as a kind of promising photovoltaic material is booming due to its low-cost, high defect tolerance, and easy fabrication, which result in the huge potential in industrial production. In the pursuit of high efficiency photovoltaic devices, high-quality absorbing layer is essential. Therefore, developing organic-inorganic hybrid perovskite thin films with good coverage, improved uniformity, and crystalline in a single pass deposition is of great concern in realizing good performance of perovskite thin-film solar cell...
May 16, 2017: Small
https://www.readbyqxmd.com/read/28507663/molecular-engineering-and-sequential-cosensitization-for-preventing-the-trade-off-effect-with-photovoltaic-enhancement
#16
Weiwei Zhang, Yongzhen Wu, Xin Li, Erpeng Li, Xiongrong Song, Huiyun Jiang, Chao Shen, Hao Zhang, He Tian, Wei-Hong Zhu
In dye-sensitized solar cells (DSSCs), it is essential to use rational molecular design to obtain promising photosensitizers with well-matched energy levels and narrow optical band gaps. However, the "trade-off" effect between the photocurrent and photovoltage is still a challenge. Here we report four benzoxidazole based D-A-π-A metal-free organic dyes (WS-66, WS-67, WS-68 and WS-69) with different combinations of π-spacer units and anchoring-acceptor groups. Either extending the π-spacer or enhancing the electron acceptor can efficiently modulate the molecular energy levels, leading to a red-shift in the absorption spectra...
March 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28505415/surface-guided-core-shell-znse-znte-nanowires-as-radial-p-n-heterojunctions-with-photovoltaic-behavior
#17
Eitan Oksenberg, Sara Martí-Sànchez, Ronit Popovitz-Biro, Jordi Arbiol, Ernesto Joselevich
The organization of nanowires on surfaces remains a major obstacle toward their large-scale integration into functional devices. Surface-material interactions have been used, with different materials and substrates, to guide horizontal nanowires during their growth into well-organized assemblies, but the only guided nanowire heterostructures reported so far are axial and not radial. Here we demonstrate the guided growth of horizontal core-shell nanowires, specifically of ZnSe@ZnTe, with control over their crystal phase and crystallographic orientations...
May 15, 2017: ACS Nano
https://www.readbyqxmd.com/read/28497691/fine-tuned-photoactive-and-interconnection-layers-for-achieving-over-13-efficiency-in-a-fullerene-free-tandem-organic-solar-cell
#18
Yong Cui, Huifeng Yao, Bowei Gao, Yunpeng Qin, Shaoqing Zhang, Bei Yang, Chang He, Bowei Xu, Jianhui Hou
Fabricating organic solar cells (OSCs) with a tandem structure has been considered an effective method to overcome the limited light absorption spectra of organic photovoltaic materials. Currently, the most efficient tandem OSCs are fabricated by adopting fullerene-derivatives as acceptors. Here, we design a new NF-acceptor with an E(opt)g of 1.68 eV for the front sub-cells and optimize the phase separation morphology of a fullerene-free active layer with an E(opt)g of 1.36 eV to fabricate the rear sub-cell...
May 12, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28497501/assessing-the-role-of-hartree-fock-exchange-correlation-energy-and-long-range-corrections-in-evaluating-ionization-potential-and-electron-affinity-in-density-functional-theory
#19
Talapunur Vikramaditya, Shiang-Tai Lin
Accurate determination of ionization potentials (IPs), electron affinities (EAs), fundamental gaps (FGs), and HOMO, LUMO energy levels of organic molecules play an important role in modeling and predicting the efficiencies of organic photovoltaics, OLEDs etc. In this work, we investigate the effects of Hartree Fock (HF) Exchange, correlation energy, and long range corrections in predicting IP and EA in Hybrid Functionals. We observe increase in percentage of HF exchange results in increase of IPs and decrease in EAs...
May 11, 2017: Journal of Computational Chemistry
https://www.readbyqxmd.com/read/28492300/rational-design-and-construction-of-well-organized-macro-mesoporous-sio2-tio2-nanostructure-toward-robust-high-performance-self-cleaning-antireflective-thin-films
#20
Binbin Jin, Junhui He, Lin Yao, Yue Zhang, Jing Li
Antireflection (AR) thin films on optical substrates are of great significance in high-performance optoelectronic devices. Here, we present a rational design and construction of well-organized macro-mesoporous nanostructure toward robust high-performance self-cleaning antireflective thin films on the basis of effective medium theory and finite difference time domain (FDTD) simulations that combine the optical design principle. A hierarchical macro-mesoporous SiO2 thin film with very high porosity and gradient refractive indexes works as a λ/4-wavelength AR layer and significantly suppresses the reflection in the range from 350 to 1200 nm...
May 11, 2017: ACS Applied Materials & Interfaces
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