Semiconductor nanocrystals can be synthesized using inexpensive, scalable, solution-based techniques, and their utility as tunable light emitters has been demonstrated in various applications, including biolabeling light-emitting devices. By contrast, the use of colloidal for optical amplification lasing limited by high input power densities that have required. In this work, we show nanoplatelets (NPLs) produce amplified spontaneous emission (ASE) with pump-fluence thresholds low 6 uJ/cm2...

There have been multiple demonstrations of amplified spontaneous emission (ASE) and lasing using colloidal semiconductor nanocrystals. However, it has proven difficult to achieve low thresholds suitable for practical use nanocrystals as gain media. Low-threshold blue ASE from is an even more challenging task. Here, we show that nanoplatelets (NPLs) with electronic structure quantum wells can produce in the red, yellow, green, regions visible spectrum high gains. In particular, blue-emitting...

Semiconductor nanorods can emit linear-polarized light at efficiencies over 80%. Polarization of in these systems, confirmed through single-rod spectroscopy, be explained on the basis anisotropy transition dipole moment and dielectric confinement effects. Here we report emission polarization macroscopic semiconductor–polymer composite films containing CdSe/CdS colloidal CdSe nanoplatelets. Anisotropic nanocrystals dispersed polymer poly butyl-co-isobutyl methacrylate (PBiBMA) stretched...

The ensemble emission spectra of colloidal InP quantum dots are broader than achievable cadmium- and lead-based dots, despite similar single-particle line widths significant efforts invested in the improvement synthetic protocols. We seek to explain origin persistently broad by investigating nature electronic states responsible for luminescence. identify a correlation between red-shifted anomalous broadening excitation luminescent colloids, suggesting trap-associated pathway highly emissive...

Nickel bis(dicarbollide) is used as a fast, one-electron outer sphere redox couple in dye-sensitized solar cells. Device performances with this anionic shuttle are investigated different electrolyte concentrations and additives, using only 0.030 M of the Ni(III) to efficiently regenerate ruthenium dye. Atomic layer deposition Al2O3 on nanoparticulate TiO2 photoanodes further improve device performances, increasing current densities almost 2-fold attaining power conversion efficiencies ∼10×...

Redox “B”ees: Rational design of a new series boron-functionalized NiIII/NiIV–bis(dicarbollide) clusters results in family robust and tunable redox shuttles (see diagram; EDG EWG denote electron-donating -withdrawing groups, respectively). This offers means to rationally control the properties dye-sensitized solar cells (DSCs), leading exceptionally high open-circuit voltages. Detailed facts importance specialist readers are published as ”Supporting Information”. Such documents...

CdSe/CdS core/shell nanorods can exhibit high photoluminescence quantum yields, but it is not yet clear what processes determine the yields and how they be controlled. Moreover, effective band alignment between core shell affects yield, its nature still under debate. We systematically studied when excited as a function of both size volume. Using time-resolved decay measurements transient-absorption spectroscopy, we found that are determined by balance radiative nonradiative recombination...

A π-extended porphyrin possessing two anchoring groups has been synthesized and successfully applied to dye-sensitized solar cells with a power conversion efficiency of 5.5%, rendering it comparable the performance N719-sensitized under conditions employed here.

The effects of anchoring groups on electron injection from adsorbate to nanocrystalline thin films were investigated by comparing kinetics through carboxylate versus phosphonate TiO2 and SnO2. In the first pair molecules, Re(LA)(CO)3Cl (ReC1A) Re(Lp)(CO)3Cl (ReC1P), [LA = 2,2'-bipyridine-4,4'-bis-CH2-COOH, Lp= 2,2'-bipyridine-4,4'-bis-CH2-PO3H2], insulated bipyridine ligand a CH2 group. second Ru(dcbpyH2)2(NCS)2 (RuN3) Ru(bpbpyH2)2(NCS)2 (RuN3P), [dcbpy 2,2'-bipyridine-4,4'-biscarboxylic...

The vibrational relaxation dynamics of pseudo-halide anions XCN- (X = O, S, Se) in polar solvents were studied to understand the effect charge on solute-to-solvent intermolecular energy transfer (IET) and solvent assisted intramolecular (IVR) pathways. T1 times CN stretch these measured by IR pump/IR probe spectroscopy, which 0-1 transition was excited, 1-2 transitions monitored follow recovery ground state decay excited state. For five solvents, H2O, D2O, CH3OH, CH3CN, (CH3)2SO, rates...

Photoinduced interfacial electron transfer (ET) from molecular adsorbates to semiconductor nanoparticles has been a subject of intense recent interest. Unlike intramolecular ET, the existence quasicontinuum electronic states in solid leads dependence ET rate on density accepting semiconductor, which varies with position adsorbate excited-state oxidation potential relative conduction band edge. For metal oxide semiconductors, their edge pH solution, leading pH-dependent rates these materials....

Insulating metal oxide coatings has been investigated as a potential approach for improving the efficiency of dye-sensitized solar cells. Thin insulating overlayers were thought to improve cell by retardation recombination kinetics injected electrons in semiconductor thin films with oxidized sensitizer molecules and electrolytes. However, how they affect electron injection dynamics is still unclear. In this work, we examined effects Al2O3 on Ru Re bipyridyl complexes sensitized...

Two porphyrin-based dyes with carboxylic acid tethers of differing acidity in both protonated and deprotonated forms were examined on ZnO nanotube electrodes. All the have similar surface coverage, but only more acidic dye form injects electrons well; this is one that corrodes ZnO. In control experiments TiO(2) nanoparticle electrodes, load inject forms. These results are consistent a requirement must partially corrode order for efficient injection to occur. Alternatively, it may possibly...

Colloidal semiconductor nanocrystals are commonly grown with a shell of second material to obtain desired physical properties, such as increased photoluminescence quantum yield. However, the growth lattice-mismatched results in strain within nanocrystal, and this has potential produce crystalline defects. Here, we study CdSe/CdS core/shell nanorods model system investigate influence core size shape on formation stacking faults nanocrystal. Using combination high-angle annular dark-field...

Factors that control photoinduced interfacial electron transfer (ET) between molecular adsorbates and semiconductor nanoparticles have been intensely investigated in recent years. In this work, the solvent dependence of ET was studied by comparing rates dye sensitized TiO2 nanocrystalline films different environments. Photoinduced from Re(LA)(CO)3Cl [LA = dcbpy 4,4'-dicarboxy-2,2'-bipyridine] (ReC1A) to thin air, pH buffer, MeOH, EtOH, DMF were measured femtosecond transient IR spectroscopy....

It is commonly assumed that after an electron-hole pair created in a semiconductor by absorption of photon the electron and hole rapidly relax to their respective lowest-energy states before recombining with one another. In heterostructure nanocrystals, however, intraband relaxation can be inhibited point where recombination occurs primarily from excited state. We demonstrate this effect using time-resolved optical measurements CdSe/CdS core/shell nanorods. For nanorods large CdSe cores,...

Ultrafast transient IR spectroscopy has been used to examine the effect of doping on interfacial electron transfer (ET) dynamics in Re(dpbpy)(CO)(3)Cl (dpbpy = 4,4'-(CH(2)PO(OH)(2))2-2,2'-bipyridine) (ReC1PO(3)) sensitized ATO (Sb:SnO(2)) nanocrystalline thin films. In films consisting particles with 0%, 2% and 10% Sb dopant, rates injection from adsorbate excited state were independent recombination increased level. The observed similar forward attributed negligible changes available...

Redox nach Belieben: Die Synthese einer Reihe neuer borfunktionalisierter NiIII/NiIV-Bis(dicarbollid)-Cluster führt zu Familie von robusten und justierbaren Redox-Shuttles. Dies bietet eine Möglichkeit zur gezielten Steuerung der Redoxeigenschaften farbstoffsensibilisierter Solarzellen, was in außergewöhnlich hohen Leerlaufspannungen resultierte. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or...

Surface enhanced Raman spectra of pyridine (Py) at Pt electrodes have been investigated as a function potential and supporting electrolyte. The results show large difference from those reported for coinage metal Ag, Au Cu, emphasising the effective involvement chemical enhancement on surfaces. At very negative (or positive) potentials, competitive coadsorption hydrogen (oroxygen-containing species) with Py, in acidic solutions, PyH+ ions prefer to dissociate into Py adsorbed surfaces even...

We propose using high-resolution stimulated Raman spectroscopy to directly measure high-speed molecular flow velocities in wind tunnels and combustive chambers. Our feasibility study indicates that speeds from Mach 0.04 up may be measured with the proposed method available laser systems. It is pointed out success of technique will make possible potential measuring all interesting parameters, i.e., species concentration, temperature, velocity, a time less than 1 μs at repetition rate 10 <sup...

Photoinduced electron transfer in a self-assembled supramolecular ladder structure comprising oligomeric porphyrin rails and ligated dipyridyltetrazine rungs was characterized by transient absorption spectroscopy direct current photoconductivity to be mainly from an oligomer (rail) the center of terminal tetrazine (rung), with remaining hole being delocalized on subsequent charge recombination 0.19 ns.