The charge-carrier dynamics process in well-designed hetero-nanostructural plasmonic photocatalysts is greatly improved through a multichannel sensitization effect, which therefore results in a significant enhancement of the efficiencies of solar-to-fuels conversion.

Blue nonblinking (>98% "on" time) ZnCdSe/ ZnS//ZnS quantum dots (QDs) with absolute fluorescence quantum yield (QY) of 92% (λ peak = 472 nm) were synthesized via a low temperature nucleation and high temperature shell growth method. Such bright nonblinking ZnCdSe/ZnS//ZnS core/shell QDs exhibit not only good emission tunability in the blue-cyan range with corresponding wavelength from 450 to 495 nm but also high absolute photoluminescence (PL) QY and superior chemical and photochemical stability. Highly efficient blue quantum dotbased light-emitting diodes (QLEDs) have been demonstrated by using nonblinking ZnCdSe/ZnS//ZnS QDs as emissive layer, and the charge−injection balance within the QD active layer was improved by introducing a nonconductive layer of poly(methyl methacrylate) (PMMA) between the electron transport layer (ETL) and the QD layer, where the PMMA layer takes the role of coordinator to impede excessive electron flux. The best device exhibits outstanding features such as maximum luminance of 14,100 cd/m 2 , current efficiency of 11.8 cd/A, and external quantum efficiency (EQE) of 16.2%. Importantly, the peak efficiency of the QLEDs with PMMA is achieved at ∼1,000 cd/m 2 and high EQE > 12% can be sustained in the range of 100 to 3,000 cd/m 2 .

The inhomogeneous interfacial electron transfer (IET) dynamics of 9-phenyl-2,3,7-trihydroxy-6-fluorone (PF)-sensitized TiO(2) nanoparticles (NPs) has been probed by a single-molecule photon-stamping technique as well as ensemble-averaged femtosecond transient absorption spectroscopy. The forward electron transfer (FET) time shows a broad distribution at the single-molecule level, indicating the inhomogeneous interactions and ET reactivity of the PF/TiO(2) NP system. The broad distribution of the FET time is measured to be 0.4 +/- 0.1 ps in the transient absorption and picoseconds to nanoseconds in the photon-stamping measurements. The charge recombination time, having a broad distribution at the single-molecule level, clearly shows a biexponential dynamic behavior in the transient absorption: a fast component of 3.0 +/- 0.1 ps and a slow component of 11.5 +/- 0.5 ns. We suggest that both strong and weak interactions between PF and TiO(2) coexist, and we have proposed two mechanisms to interpret the observed IET dynamics. A single-molecule photon-stamping technique and ensemble-averaged transient absorption spectroscopy provide efficient "zoom-in" and "zoom-out" approaches for probing the IET dynamics. The physical nature of the observed multiexponential or stretched-exponential ET dynamics in the ensemble-averaged experiments, often associated with dynamic and static inhomogeneous ET dynamics, can be identified and analyzed by single-molecule spectroscopy measurements.

The ultrafast transfer of plasmon-induced hot electrons is considered an effective kinetics process to enhance the photoconversion efficiencies of semiconductors through strong localized surface plasmon resonance (LSPR) of plasmonic nanostructures. Although this classical sensitization approach is widely used in noble-metal-semiconductor systems, it remains unclear in nonmetallic plasmonic heterostructures. Here, by combining ultrafast transient absorption spectroscopy with theoretical simulations, IR-driven transfer of plasmon-induced hot electron in a nonmetallic branched heterostructure is demonstrated, which is fabricated through solvothermal growth of plasmonic W O nanowires (as branches) onto TiO electrospun nanofibers (as backbones). The ultrafast transfer of hot electron from the W O branches to the TiO backbones occurs within a timeframe on the order of 200 fs with very large rate constants ranging from 3.8 × 10 to 5.5 × 10 s . Upon LSPR excitation by low-energy IR photons, the W O /TiO branched heterostructure exhibits obviously enhanced catalytic H generation from ammonia borane compared with that of W O nanowires. Further investigations by finely controlling experimental conditions unambiguously confirm that this plasmon-enhanced catalytic activity arises from the transfer of hot electron rather than from the photothermal effect.

Due to the unique optical properties, colloidal quantum dots (QDs) are excellent candidates for developing next-generation display and solid-state lighting technologies. However, some factors including photoluminescence blinking and Förster resonance energy transfer (FRET) still affect their practical applications. Herein, a series of ZnCdSe-based core/shell QDs with low optical polydispersity have been successfully synthesized by a “low-temperature injection and high-temperature growth” precisely controlled method. The alloyed ZnCdSe core with a certain ratio of Cd and Zn was presynthesized first. Followed by accurate ZnS shell growth, the as-synthesized core/shell QDs are nonblinking with the nonblinking threshold volume of ∼137 nm3. The PL decay dynamics are all single-exponential for both QDs in solutions and close-packed solid films when ZnS shell thickness varying from 2 to 20 monolayers. FRET can be effectively suppressed after growing 10 monolayers of ZnS shell. All of these superb characteristics including nonblinking, single-exponential PL decay dynamics and suppressed FRET can be beneficial to high-quality QD-based light-emitting devices (QLEDs). By applying the ZnCdSe-based core/shell QDs with 10 monolayers ZnS shell, the highest external quantum efficiency of ∼17% was reached, which could compare favorably with the highest efficiency of green QLEDs with traditional multilayered structures.

Many useful energy transfer concepts originate from nature. For example, fluorescent proteins have evolved to perform energy transfer with extraordinary efficiency. While fluorescent proteins are commonly used as probes of protein localization in biological cells, their native functions in the host organisms are light absorption, energy transfer to other proteins, or light emission to the environment. 1 For example, green fluorescent protein (GFP) from the jellyfish Aequorea victoria absorbs energy transferred from blue luminescent protein (aequorin) and then emits green light. 1,2 Cyanobacteria and eukaryotic algae (red algae, glaucophytes, and criptomonads) contain three classes of fluorescent phycobiliproteins: phycoerythrins, allophycocyanins, and phycocyanins. 3 These are assembled into photosynthetic protein complexes called phycobilisomes. 3,4 The phycobiliproteins B-phycoerythrin (B-PE) and R-phycoerythrin (R-PE) each contain more than 30 phycoerythrobilin (PEB) and phycourobilin (PUB) chromophores that are assembled in a 240 kDa multimeric complex (Rβ) 6 γ. Hence, phycobilin chromophores, which are linear tetrapyrole compounds bound to polypeptide chains by thioether bonds, are responsible for the excellent spectroscopic properties of phycobiliproteins as well as energy transfer involving phycobiliproteins. 4 Phycobilisomes absorb sunlight and then transfer energy via F€ orster resonance energy transfer (FRET) to chlorophyll a. 4 Phycobiliproteins possess unique characteristics that make them suitable for fluorescence detection and energy transfer, which include extremely high absorption coefficients over a broad part

Abstract. Air quality and visibility are strongly influenced by aerosol loading, which is driven by meteorological conditions. The quantification of their relationships is critical to understanding the physical and chemical processes and forecasting of the polluted events. We investigated and quantified the relationship between PM 2.5 (particulate matter with aerodynamic diameter is 2.5 µm and less) mass concentration, visibility and planetary boundary layer (PBL) height in this study based on the data obtained from four long-lasting haze events and seven fog-haze mixed events from January 2014 to March 2015 in Beijing. The statistical results show that there was a negative exponential function between the visibility and the PM 2.5 mass concentration for both haze and fog-haze mixed events (with the same R 2 of 0.80). However, the fog-haze events caused a more obvious decrease of visibility than that for haze events due to the formation of fog droplets that could induce higher light extinction. The PM 2.5 concentration had an inversely linear correlation with PBL height for haze events and a negative exponential correlation for fog-haze mixed events, indicating that the PM 2.5 concentration is more sensitive to PBL height in fog-haze mixed events. The visibility had positively linear correlation with the PBL height with an R 2 of 0.35 in haze events and positive exponential correlation with an R 2 of 0.56 in foghaze mixed events. We also investigated the physical mechanism responsible for these relationships between visibility, PM 2.5 concentration and PBL height through typical haze and fog-haze mixed event and found that a double inversion layer formed in both typical events and played critical roles in maintaining and enhancing the long-lasting polluted events. The variations of the double inversion layers were closely associated with the processes of long-wave radiation cooling in the nighttime and short-wave solar radiation reduction in the daytime. The upper-level stable inversion layer was formed by the persistent warm and humid southwestern airflow, while the low-level inversion layer was initially produced by the surface long-wave radiation cooling in the nighttime and maintained by the reduction of surface solar radiation in the daytime. The obvious descending process of the upper-level inversion layer induced by the radiation process could be responsible for the enhancement of the lowlevel inversion layer and the lowering PBL height, as well as high aerosol loading for these polluted events. The reduction of surface solar radiation in the daytime could be around 35 % for the haze event and 94 % for the fog-haze mixed event. Therefore, the formation and subsequent descending processes of the upper-level inversion layer should be an important factor in maintaining and strengthening the longlasting severe polluted events, which has not been revealed in previous publications. The interactions and feedbacks between PM 2.5 concentration and PBL height linked by radiation process caused a more significant an...

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