Author
Liangliang Han
Bio: Liangliang Han is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Polymer solar cell & Organic solar cell. The author has an hindex of 21, co-authored 67 publications receiving 1239 citations.
Papers
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TL;DR: The terbium complex Tb(acac)2AA (acac: acetyl acetone, AA: acrylic acid) was incorporated into polystyrene (PS) matrix and electrospun into various composite fibers and the fluorescence lifetime of the 5D4 state of Tb3+ ion in the composite fibers was shorter than that of the Tb complex.
Abstract: The europium complex Eu(TTA)3(TPPO)2 (TTA = thenoyltrifluoroacetone, TPPO = triphenylphosphine oxide) was incorporated into poly(methyl methacrylate) (PMMA, Mw ≈ 350 000), polystyrene (PS, Mw ≈ 250 000), poly(vinyl pyrrolidone) (PVP, Mw ≈ 1 300 000) matrixes and electrospun into various composite fibers. The thermal stability of these composite fibers is better than that of the pure europium complex. Their photoluminescence properties were studied in comparison to those of the pure complex. The results indicate that, in all of the composite fibers, the excitation bands of the ligands split into different components because of the distorted crystal field, which reduces the degree to which the 5D0−7F0 transition is parity-forbidden. In addition, the thermal stability of the photoluminescence of Eu3+ in the composite fibers is considerably improved over that of the pure complex. Also, the Eu(TTA)3(TPPO)2/PS composite fibers exhibit better photostability upon exposure to ultraviolet light. In the Eu(TTA)3(TPP...
108 citations
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53 citations
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TL;DR: In this article, the authors demonstrate organic photovoltaic (PV) and ultraviolet (UV) photodetector devices using 1,3,5-tris(3-methylphenylphenyl-phenylamino)-triphenyamine and 1, 3, 5 tris(N-phenylbenzimidazol-2-yl)-benzene to function as donor (D) and acceptor (A), respectively.
51 citations
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TL;DR: In this paper, a two-dimensional organic small molecule, DCA3T(T-BDT), was designed and synthesized for solution-processed organic solar cells (OSCs).
Abstract: A new two-dimensional (2D) organic small molecule, DCA3T(T-BDT), was designed and synthesized for solution-processed organic solar cells (OSCs). DCA3T(T-BDT) exhibited a deep HOMO energy level (−5.37 eV) and good thermal stability. The morphologies of the DCA3T(T-BDT):[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) blends were investigated by atomic force microscopy and the crystallinity was explored by X-ray diffraction (XRD) and 2D grazing incidence wide-angle X-ray scattering (GIWAXS), respectively. The morphologies of the blends were strongly influenced by the blend ratio of DCA3T(T-BDT):PC61BM and annealing temperature. The effect of thermal annealing on the photovoltaic performance of DCA3T(T-BDT)-based small molecule organic solar cells (SMOSCs) was studied in detail. When DCA3T(T-BDT) was used as a donor with PC61BM as an acceptor, high efficiency SMOSCs with a power conversion efficiency of 7.93%, a high Voc of 0.95 V, Jsc of 11.86 mA cm−2 and FF of 0.70 were obtained by a thermal annealing process at only 60 °C, which offers obvious advantages for large scale production compared with solvent additive or interfacial modification treatment.
50 citations
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TL;DR: In this paper, two polymer donors (PBB1-Cl and PBB2-Cl) with different side chains were investigated as the third component to fine regulate morphology and molecular accumulation of the active layer to improve the performance of OSCs.
Abstract: The flexibility and stability of organic solar cells (OSCs) are becoming hotspot research due to their practical applications. Molecular arrangement and network morphology of the active layer are important factors affecting the flexibility and stability of OSCs. Here, two polymer donors (PBB1-Cl and PBB2-Cl) with different side chains were investigated as the third component to finely regulate morphology and molecular accumulation of the active layer to improve the performance of OSCs. Both third components show complementary absorption spectra and good compatibility. The good planarity of PBB1-Cl and PBB2-Cl significantly increases intermolecular overlap to promote the charge transfer in the active layer. In addition, the steric hindrance of the one-dimensional side chain of PBB1-Cl enhanced the intermolecular close packing and entanglement of the active layer. As a result, the tensile endurance of PM6:PBB1-Cl:Y6-BO-4Cl ternary blend film reached 4.6 times (26.86%) of the PM6:Y6-BO-4Cl binary blend film. Furthermore, the power conversion efficiency (PCE) increased from 15.83% for PM6:Y6-BO-4Cl based binary OSCs to 17.36% for PBB1-Cl based rigid ternary OSCs, and the flexible OSCs increased from 13.44% to 14.96%, respectively. 17.36% efficiency of PBB1-Cl based ternary OSCs is the highest value in OSCs with elongation at the break of active layer exceeding 25% so far. Further, the PCEs of PBB1-Cl-based flexible ternary OSCs still remain above 74% within 500 cycles of bending with a diameter of 10 mm or annealing at 100 °C for 24 hours, which is mainly attributed to the smaller surface energy difference between PBB1-Cl-based ternary blend film and transport layers, higher glass transition temperature and larger elongation at break of the active layer. All results suggest that enhancing intermolecular overlapping fasten packing in the active layer has great potential in improving the photovoltaic performance, mechanical and thermal stability of OSCs.
48 citations
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01 May 1993
TL;DR: Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems.
Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.
29,323 citations
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TL;DR: This critical review describes the latest developments in the sensitization of near-infrared luminescence, "soft" luminescent materials (liquid crystals, ionic liquids, ionogels), electroluminescentmaterials for organic light emitting diodes, with emphasis on white light generation, and applications in luminecent bio-sensing and bio-imaging based on time-resolved detection and multiphoton excitation.
Abstract: Recent startling interest for lanthanide luminescence is stimulated by the continuously expanding need for luminescent materials meeting the stringent requirements of telecommunication, lighting, electroluminescent devices, (bio-)analytical sensors and bio-imaging set-ups. This critical review describes the latest developments in (i) the sensitization of near-infrared luminescence, (ii) “soft” luminescent materials (liquid crystals, ionic liquids, ionogels), (iii) electroluminescent materials for organic light emitting diodes, with emphasis on white light generation, and (iv) applications in luminescent bio-sensing and bio-imaging based on time-resolved detection and multiphoton excitation (500 references).
2,895 citations
01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg
1,652 citations
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TL;DR: Blue phosphorescence approaching the theoretical efficiency has also been achieved, which may overcome the final obstacle against the commercialization of full color display and white light sources from phosphorescent materials.
Abstract: Although organic light-emitting devices have been commercialized as flat panel displays since 1997, only singlet excitons were emitted. Full use of singlet and triplet excitons, electrophosphorescence, has attracted increasing attentions after the premier work made by Forrest, Thompson, and co-workers. In fact, red electrophosphorescent dye has already been used in sub-display of commercial mobile phones since 2003. Highly efficient green phosphorescent dye is now undergoing of commercialization. Very recently, blue phosphorescence approaching the theoretical efficiency has also been achieved, which may overcome the final obstacle against the commercialization of full color display and white light sources from phosphorescent materials. Combining light out-coupling structures with highly efficient phosphors (shown in the table-of-contents image), white emission with an efficiency matching that of fluorescent tubes (90 lm/W) has now been realized. It is possible to tune the color to the true white region by changing to a deep blue emitter and corresponding wide gap host and transporting material for the blue phosphor. In this article, recent progresses in red, green, blue, and white electrophosphorescent materials for OLEDs are reviewed, with special emphasis on blue electrophosphorescent materials.
1,240 citations
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TL;DR: This review suggests that organic phototransistors have a large potential to be used in a variety of optoelectronic peculiar applications, such as a photo-sensor, opto-isolator, image sensor, optically controlled phase shifter, and opto -electronic switch and memory.
Abstract: While organic electronics is mostly dominated by light-emitting diodes, photovoltaic cells and transistors, optoelectronics properties peculiar to organic semiconductors make them interesting candidates for the development of innovative and disruptive applications also in the field of light signal detection. In fact, organic-based photoactive media combine effective light absorption in the region of the spectrum from ultraviolet to near-infrared with good photogeneration yield and low-temperature processability over large areas and on virtually every substrate, which might enable innovative optoelectronic systems to be targeted for instance in the field of imaging, optical communications or biomedical sensing. In this review, after a brief resume of photogeneration basics and of devices operation mechanisms, we offer a broad overview of recent progress in the field, focusing on photodiodes and phototransistors. As to the former device category, very interesting values for figures of merit such as photoconversion efficiency, speed and minimum detectable signal level have been attained, and even though the simultaneous optimization of all these relevant parameters is demonstrated in a limited number of papers, real applications are within reach for this technology, as it is testified by the increasing number of realizations going beyond the single-device level and tackling more complex optoelectronic systems. As to phototransistors, a more recent subject of study in the framework of organic electronics, despite a broad distribution in the reported performances, best photoresponsivities outperform amorphous silicon-based devices. This suggests that organic phototransistors have a large potential to be used in a variety of optoelectronic peculiar applications, such as a photo-sensor, opto-isolator, image sensor, optically controlled phase shifter, and opto-electronic switch and memory.
1,081 citations