Interface Energetics and Engineering of Organic Heterostructures in Organic Photovoltaic Cells
Organolead Trihalide Perovskite Materials for Efficient Light Emitting Diodes
Organolead Trihalide Perovskite Materials for Efficient Light Emitting Diodes
Organolead trihalide perovskite materials have been attracting increasing attention due to their promising role in solid solar cells. Several advantages make them potential candidates for optoelectronics: 1) solution- or/and vapor-processed preparation at low temperature; 2) tunable optical bandgap, wide absorption spectrum but narrow photoluminescence peaks; 3) long carrier life time, large diffusion length and high charge mobility; 4) various nanostructures via tuning capping agents and solvents. In this review, we summarize recent attempts toward efficient LEDs based on organolead trihalide perovskite materials. The strategies of materials science, device design, interface engineering are highlighted. Recent development and future perspectives are summarized for practical perovskite light technologies.
Flexible and stretchable electrodes for next generation polymer electronics: a review
Transparent conductive electrodes play a significant role in the fabrication and development of optoelectronic devices. As next generation optoelectronic devices trend towards mobile and wearable devices, the added attribute of flexibility or stretchability for these electrodes becomes increasingly important. However, mechanical requirements aside, transparent conductive electrodes must still retain high transparency and conductivity, with the metrics for these parameters being compared to the standard, indium tin oxide. In the search to replace indium tin oxide, two materials that have risen to the forefront are carbon nanotues and silver nanowires due to their high transparency, conductivity, mechanical compliance, and ease of fabrication. This review highlights recent innovations made by our group in electrodes utilizing carbon nanotubes and silver nanowires, in addition to the use of these electrodes in discrete devices and integrated systems.
A Self-Catalytic Role of Methanol in PNP-Ru Pincer Complex Catalysed Dehydrogenation
Solution-processable graphenes by covalent functionalization of graphene oxide with polymeric monoamines
We develop here a simple wet chemistry to prepare covalent functionalized graphenes (FGs) through epoxide aminolysis espe-cially under alkaline aqueous condition. Remarkably, a series of typical monoamines, such as industrial Huntsman Jeffamine® M-2070 and M-2005 polymer with hydrophilic or hydrophobic polyetheramine chains, positively-charged 2-amino-N,N,N-trimethylpropanaminium, negatively-charged sulfanilic acid, even oligopeptide sequence, can be effectively grafted on the platelets of graphene oxide precursor with covalent functionalization and partially reduced features. This strategy provides the researchers a facile and convenient approach to design and synthesize solution processable, biocompatible and functionalized graphenes for the potent applications in electronic inks, drug carriers and biomedicines. Expansion of the current study is actively undergoing in our laboratory.
Imaging Cellular Distribution of Fluorescent Supermolecular Nanofibers
Visualization of α1-Adrenergic Receptors with Phenylpiperazine-based Fluorescent Probes
Several novel fluorescent probes targeting α1-adrenergic receptors were well designed and synthesized by conjugating phenylpiperazine pharmacophore with coumarin and fluorescein fluorophores. These compounds showed suitable fluorescence property, high receptor affinity, and low cytotoxicity. Moreover, the cell imaging results displayed that these probes can be effective tools for the real-time detection of ligand−receptor interactions, as well as the visualization and location of α1-adrenergic receptors in living cells.
Biosensing strategy based on photocurrent quenching of quantum dots via energy resonance absorption
The First Enantioselective Total Synthesis of (+)-Preussin B and an Improved Synthesis of (+)-Preussin By Step-economical Methods
The first enantioselective total synthesis of (+)-preussin B and an improved synthesis of the antifungal alkaloid (+)-preussin are described. Our approach relied on the four step-economical synthetic methods developed in our laboratory: (1) the cis-diastereoselective reductive dehydroxylation of hemiaminals; (2) the direct amide/ lactam reductive alkylation; (3) the one-pot N,O-bisdebenzylation–N-methylation; and (4) the one-step synthesis of malimide from malic acid. Both total syntheses are quite concise, which have been achieved in six steps, and give overall yields of 25.7% and 27.6%, respectively.
Fully degradable brush polymers with polycarbonate backbones and polylactide side chains
Side-chain engineering of high-efficiency conjugated polymer photovoltaic materials
Loop formation and stability of self-avoiding polymer chains
Using 3-dimensional Langevin dynamics simulations, we investigated the dynamics of loop formation of chains with excluded volume interactions, and the stability of the formed loop. The mean looping time τl scales with chain length N and corresponding scaling exponent α increases linearly with the capture radius scaled by the Kuhn length a/l due to the effect of finite chain length. We also showed that the probability density function of the loop time is well fitted by a single exponential. Finally, we found that the mean unlooping time τu hardly depends on chain length N for a given a/l and that the stability of a formed loop is enhanced with increasing a/l.
The effect of interfacial diffusion on device performance of
polymer solar cells: A quantitative view by active-layer doping
Low band-gap benzodithiophene-thienothiophenecopolymers: The effect of dual two-dimensional substitutions on optoelectronic properties
A new oligobenzodithiophene end-capped with 3-ethyl-rhodanine groups for organic solar cells with highopen-circuit voltage
Alcohol/water-soluble porphyrins as cathode interlayers in high- performance polymer solar cells
Effect of electron-withdrawing units on triphenylamine-based small molecules for solution-processed organic solar cells
Organic small molecules (TPA-BT3T, TPA-PT3T, and TPA-DFBT3T) using triphenylamine as a donor unit, terthiophene as a bridge, and benzo-2,1,3-thiadiazole (BT), [1,2,5]thiadiazolo[3,4-c]pyridine (PT) or 5,6-difluorobenzo[c][1,2,5]thiadiazole (DFBT) as an acceptor unit were designed and synthesized through Suzuki coupling reactions. These molecules exhibited good thermal stability with decomposition temperatures over 380 oC and broad absorption from 300 to 700 nm. Photovoltaic devices were fabricated with these small molecules as donors and PC71BM as an acceptor. The TPA-BT3T based devices exhibited a power conversion efficiency of 2.89%, higher than those of the TPA-PT3T- and TPA-DFBT3T-based devices (1.34% and 1.54% respectively). The effects of electron-withdrawing units on absorption, energy level, charge transport, morphology, and photovoltaic properties also were investigated.
Constructing vertical phase separation of polymer blends via mixed solvents to enhance their photovoltaic performance
A New Class of Ion–ion Interaction：Z-bond
Carbon-free Cu2ZnSn(S,Se)4 film prepared via a non-hydrazine route
The kesterite Cu2ZnSn(S,Se)4 (CZTSSe) is an ideal candidate for light harvesting materials in earth-abundant low-cost thin-film solar cells (TFSC). Although the solution-based processing is a most promising approach to achieve low-cost solar cells with high power conversion efficiency, the issues of poor crystallinity and carbon residue in CZTSSe thin films are still challenging. Herein, a non-hydrazine solution-based method was reported to fabricate highly crystallized and carbon-free kesterite CZTSSe thin films. Interestingly, it was found that the synthetic atmosphere of metal organic precursors have a dramatic impact on the morphology and crystallinity of CZTSSe films. By optimizing the processing parameters, we are able to obtain a kesterite CZTSSe film composed of compact large crystal grains with trace carbon residues. Also, a
viable reactive ion etching (RIE) processing with optimized etching conditions was then developed to successfully eliminate trace carbon residues on the surface of the CZTSSe film.
The Fourier space restricted Hartree-Fock method for the electronic structure calculation of linear poly(tetrafluoroethylene)
Building on the pioneering work of J.-M. Andre and working in the laboratory he founded, the authors have developed a code called ft-1d to make Hartree-Fock electronic structure computations for stereoregular polymers using Ewald-type convergence acceleration methods. That code also takes full advantage of all line-group symmetries to calculate only the minimal set of two-electron integrals and to optimize the computation of the Fock matrix. The present communication reports a benchmark study of the ft-1d code using polytetrauoroethylene (PTFE) as a test case. Our results not only con rm the algorithmic correctness of the code through agreement with other studies where they are applicable, but also show that the use of convergence acceleration enables accurate results to be obtained in situations where other widely-used codes (e.g., plh and crystal) fail. It is also found that full attention to the line-group symmetry of the PTFE polymer leads to an increase of between one and two orders of magnitude in the speed of computation. The new code can therefore be viewed as extending the range of electronic-structure computations for stereoregular polymers beyond the present scope of the successful and valuable code crystal.
Stable ZnO/ionic liquid hybrid materials: novel dual-responsive superhydrophobic layers to light and anions
Novel dual-responsive superhydrophobic hybrid materials, ZnO/SAMs (self-assembled monolayers) of ionic liquids (ILs) with different counter-anions (I−, BF4−, PF6− and Tf2N−), were synthesized and characterized. ZnO nanoparticles were first deposited on glass surfaces to produce roughness. Next, SAMs of fluorinated-alkyl-3-(3-triethoxysilylpropyl)-4,5-dihydro-imidazoliumiodide (abb. [C8Ftespim]I) were grafted onto these surfaces via -Si-O- covalent bonds using self-assembly technique. The I− ion could be subsequently exchanged with BF4−, PF6− or Tf2N− through a simple aqueous anion-exchange reaction. The ZnO/ILs hybrid layers were characterized by atomic-force microscope (AFM), scanning-electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Their wettability was estimated through the measurements of static and dynamic contact angles (CAs). Compared to corresponding films of ZnO/[C8Ftespim]I with CAs 140.7 ± 2.0o, films of ZnO/[C8Ftespim]PF6 and ZnO/[C8Ftespim]Tf2N showed CAs with 154.0 ± 2.0o and 152.0 ± 2.0o, respectively, that remained for a long time. This result suggests that anion-exchange can afford superhydrophobic materials. In addition, the wettability of ZnO/[C8Ftespim]X hybrid layers can be reversibly switched by altering ultraviolet (UV) irradiation and dark storage, which shows a photo-induced reversible switch of wettability. The synergistic action of ZnO nanoparticles and SAMs of ILs produced light-anion dual-responsive superhydrophobic materials with ideal stability.
Recent advances in plasmonic organic photovoltaics
Two-dimensional photovoltaic copolymers with spatial D-A-D structures: Synthesis, characterization and hetero-atom effect
A series of two-dimensional (2D) conjugated copolymers with spatial D-A-D structures (PTNBTB, PTCBTB, and PTSBTB) consisting of hetero-atom-bridged dithiophene and phenylvinyl-substituted benzothiadiazole blocks in the main chain have been designed, synthesized, and characterized. The structure–property relationships of the resulting copolymers were systematically investigated. The effects of the bridging atoms (N, C, and Si) on their thermal, optical, electrochemical and charge-transporting properties were also studied. PTNBTB exhibits a smaller band gap with red-shifted absorption, whereas PTSBTB possesses deeper HOMO level and higher hole mobility than PTCBTB or PTSBTB. Bulk heterojunction (BHJ) solar cells were fabricated and characterized with the conventional configuration of ITO/PEDOT:PSS/copolymer:PC71BM (1:1)/Ca/Al. As expected, PTSBTB devices showed the highest PCE, up to 4.01%, which was due to the lower HOMO level, higher carrier mobility, and stronger optical response as well as the finer nanoscale phase separation of the pristine polymer and/or the corresponding blending active layer with PC71BM. The primary results offer useful insights in designing 2D copolymers with spatial D-A-D backbone and different hetero-atom bridged donor units to finely tune the absorptions, electronic energy levels, carrier mobilities and the photovoltaic properties.