Ligand-Tuned Multi-Color Luminescence of Single Aluminum (III) Ion Atomic Centers and Their Selective Sensitivity to Different Metal Ions.

Achieving multi-color luminescence with a single atomic center in transition metal complexes is a challenge. In this work, luminescent materials with tunable emission properties were realized by complexation between aluminum (III) ions with the ligands 3-hydroxyflavone (3-HF) and 5,7-dichloro-8-hydroxyquinoline (DCHQ). Aluminum (III) complexes with a single ligand emitted blue from 3-HF and green from DCHQ. High quantum yields (QYs) of 29.42% and 37.00% were also obtained, respectively. DFT calculations revealed details of the photophysical properties of the complexes. Correspondingly, cyan light emission was obtained if these two complexes were mixed together, from which the emission wavelength was located at 470 nm and the QY was 20.52%, under 290 nm excitation. More importantly, the cyan light emitted by the mixtures had selective sensitivity to different metal ions, resulting in either quenching the fluorescence (in the case of Fe3+) or enhancing the fluorescence (in the case of In3+). The fluorescence enhancement effect of In3+ on metal complexes has not been previously reported, neither for transition metal nor lanthanide ions. The linear quenching behavior of Fe3+ functions in the 50-700 µM concentration range, and the linear enhancement behavior of In3+ is demonstrated in the 300-800 mM concentration range.

Subtle Side Chain Triggers Unexpected Two-Channel Charge Transport Property Enabling 80% Fill Factors and Efficient Thick-Film Organic Photovoltaics.

To clearly show how important the impact of side chains on organic solar cells (OSCs) is, we designed three acceptors IDIC-CxPh (x = 4, 5, or 6) via subtle side-chain regulation. Despite this small change, significant distinctions were detected. IDIC-C4Ph devices achieve an optimal efficiency of 13.94% under thermal annealing, but thermal-assistant solvent-vapor annealing hugely suppresses the efficiencies to 10%. However, the C6Ph side chain endows extremely disordered stacking orientations, generating moderate efficiencies of ~12.50%. Excitingly, the IDIC-C5Ph affords an unexpected two-channel π-π charge transport (TCCT) property, boosting the fill factor (FF) by up to 80.02% and efficiency to 14.56%, ranking the best among five-ring fused-ladder-type acceptors. Impressively, the special TCCT behavior of IDIC-C5Ph enables 470 nm thick-film OSC with a high FF of up to 70.12% and efficiency of 13.01%, demonstrating the great promise in fabricating large-scale OSCs.

An Effective Strategy to Design a Large Bandgap Conjugated Polymer by Tuning the Molecular Backbone Curvature.

With the significant progress of low bandgap non-fullerene acceptors, the development of wide bandgap (WBG) donors possessing ideal complementary absorption is of crucial importance to further enhance the photovoltaic performance of organic solar cells. An ideal strategy to design WBG donors is to down-shift the highest occupied molecular orbital (HOMO) and up-shift the lowest unoccupied molecular orbital (LUMO). A properly low-lying HOMO of the donor is favorable to obtaining a high open-circuit voltage, and a properly high-lying LUMO of the donor is conductive to efficient exciton dissociation. This work provides a new strategy to enlarge the bandgap of a polymer with simultaneously decreased HOMO and increased LUMO by increasing the polymer backbone curvature. The polymer PIDT-fDTBT with a large molecular backbone curvature shows a decreased HOMO of -5.38 eV and a prominently increased LUMO of -3.35 eV relative to the linear polymer PIDT-DTBT (EHOMO = -5.30 eV, ELUMO = -3.55 eV). The optical bandgap of PIDT-fDTBT is obviously broadened from 1.75 to 2.03 eV. This work demonstrates that increasing the polymer backbone curvature can effectively broaden the bandgap by simultaneously decreasing HOMO and increasing LUMO, which may guide the design of WBG conjugated materials.

Recent advances, challenges and prospects in ternary organic solar cells.

The past decade has seen a tremendous development of organic solar cells (OSCs). To date, high-performance OSCs have boosted power conversion efficiencies (PCEs) over 17%, showing bright prospects toward commercial applications. Compared with binary OSCs, ternary OSCs, by introducing a third component as a second donor or acceptor into the active layer, have great potential in realizing outstanding photovoltaic performance. Herein, a comprehensive review of the recent advances of ternary solar cells is presented. According to the chemical components of active layer materials, we classify the ternary systems into four categories, including polymer/small molecule/small molecule, polymer/polymer/small molecule, all-polymer and all-small-molecule types. The relationships among the photovoltaic materials structure and weight ratio, active layer morphology and photovoltaic performance are systematically analyzed and summarized. The features and design strategies of each category are also discussed and summarized. Key issues and challenges faced in ternary OSCs are pointed out, and potential strategies and solutions are proposed. This review may provide guidance for the field of ternary OSCs.

Strong enhanced efficiency of natural alginate for polymer solar cells through modification of the ZnO cathode buffer layer.

Sodium alginate (SA), as a natural marine biopolymer, possesses many merits such as super-easy accessibility from the ocean, low cost, nontoxicity, and no synthesis for practical application. For the chemical structure, SA has enough lone electron pairs of oxygen atoms in the backbone and short branched chains, which is expected to passivate oxygen vacancy on the surface of the ZnO cathode buffer layer to improve the photovoltaic performance. Herein, it was applied to modify the surface trap of the ZnO layer in fullerene and non-fullerene polymer solar cells (PSCs). The defects were successfully reduced, and the trap-assisted recombination decreased. In a PTB7-Th:PC71BM system, power conversion efficiency (PCE) was improved from 8.06% to 9.36%. In the PM6:IT-4F system, PCE was enhanced from 12.13% to 13.08%. The addition of SA did not destroy the stability of the device. Overall, this work demonstrates the potential for preparing devices with long-time stability and industrial manufacture of PSCs by using biological materials in the future.

Heterostructure NaGdF4:Yb,Er anchored on MIL-101 for promoting photoelectronic response and photocatalytic activity.

Herein, NaGdF4:Yb,Er nanoparticles were anchored on a Material of Institute Lavoisier (MIL-101). In the well-defined heterostructure, MIL-101/NaGdF4:Yb,Er, the absorption and fluorescence could be tuned, and the composite facilitated the separation of photogenerated electron-hole pairs. Moreover, the heterostructure displayed a higher photocurrent and better degradation ability for Rhodamine B that its individual components owing to its synergistic effect.

Classification, Synthesis, and Application of Luminescent Silica Nanoparticles: a Review.

Luminescent materials are of worldwide interest because of their unique optical properties. Silica, which is transparent to light, is an ideal matrix for luminescent materials. Luminescent silica nanoparticles (LSNs) have broad applications because of their enhanced chemical and thermal stability. Silica spheres of various sizes could be synthesized by different methods to satisfy specific requirements. Diverse luminescent dyes have potential for different applications. Subject to many factors such as quenchers, their performance was not quite satisfying. This review thus discusses the development of LSNs including their classification, synthesis, and application. It is the highlight that how silica improves the properties of luminescent dye and what role silica plays in the system. Further, their applications in biology, display, and sensors are also described.

Photodeposition of palladium nanoparticles on a porous gallium nitride electrode for nonenzymatic electrochemical sensing of glucose.

A nonenzymatic electrochemical glucose sensor is described that was obtained by in situ photodeposition of high-density and uniformly distributed palladium nanoparticles (PdNPs) on a porous gallium nitride (PGaN) electrode. Cyclic voltammetric and chronoamperometric techniques were used to characterize the performance of the modified electrode toward glucose. In 0.1 M NaOH solution, it has two linear detection ranges, one from 1 µM to 1 mM, and another from 1 to 10 mM, and the detection limit is 1 µM. The electrode is repeatable, highly sensitive, fast and long-term stable. It was applied to the quantitation of serum glucose where it displayed accurate current responses. Graphical abstract A novel nonenzymatic electrochemical glucose sensor was developed by in situ photodeposition of palladium nanoparticles on the porous gallium nitride electrode.

Preparation of Hybrid Nanoparticle Nucleating Agents and Their Effects on the Crystallization Behavior of Poly(ethylene terephthalate).

In this research contribution, the primary objective was to enhance the crystallization behavior of poly(ethylene terephthalate) (PET). To accomplish this tack, three kinds of new nucleating agents SiO2-diethylene glycol-LMPET (PET-3), SiO2-triethylene glycol-LMPET(PET-4) and SiO2-tetraethylene glycol-LMPET (PET-5) nucleating agents were prepared via grafting different oligomers (diethylene glycol; triethylene glycol and tetraethylene glycol) to the surface of nano-SiO2 and then linking to the low molecular weight poly(ethylene terephthalate) (LMPET). These nano-particle nucleating agents facilitated the crystallization of PET. Differential scanning calorimetry (DSC) studies of the composites that pure PET blended with PET-3, PET-4 and PET-5 indicated that the longer ethoxy segment in the nucleating agents exhibited (i) higher degrees of crystallinity; (ii) faster rates of crystallization; and (iii) higher crystallization temperatures. The Jeziorny method was employed to analyze the non-isothermal crystallization kinetics of the composites. These works demonstrated that the PET-3, PET-4 and PET-5 were attractive nucleating agents for poly(ethylene terephthalate), and the longer the chain length of the ethoxy segment in the nucleating agents, the more efficient the nucleation effect.