Abstract:Owing to the difficulty in comprehensively characterizing nanocrystal (NC) surfaces,c lear guidance for ligand design is lacking. In this work, as eries of bidentate bis-(pyridine) anthracene isomers (2,3-PyAn, 3,3-PyAn, 2,2-PyAn) that differ in their binding geometries were designed to find the best complementary fit to the NC surface.T he efficiency of triplet energy transfer (TET) from the CdSe NC donor to ad iphenylanthracene (DPA) acceptor mediated by these isomers was used as ap roxy for the efficacy of … Show more
We functionalizePbS nanocrystals with the organic semiconductor Zn b-tetraaminophthalocyanine to design an anostructured solid-state material with frequent organicinorganic interfaces.B ytransient absorption and fluorescence spectroscopy, we investigate the optoelectronic response of this hybrid material under near-infrared excitation to find efficient charge transfer from the nanocrystals to the molecules.W e demonstrate that the material undergoes cooperative sensitization of two nanocrystals followed by photon upconversion and singlet emission of the organic semiconductor.T he upconversion efficiency resembles that of comparable systems in solution, which we attribute to the large amount of interfaces present in this solid-state film. We anticipate that this synthetic strategy has great prospects for increasing the open-circuit voltage in PbS nanocrystal-based solar cells.
We functionalizePbS nanocrystals with the organic semiconductor Zn b-tetraaminophthalocyanine to design an anostructured solid-state material with frequent organicinorganic interfaces.B ytransient absorption and fluorescence spectroscopy, we investigate the optoelectronic response of this hybrid material under near-infrared excitation to find efficient charge transfer from the nanocrystals to the molecules.W e demonstrate that the material undergoes cooperative sensitization of two nanocrystals followed by photon upconversion and singlet emission of the organic semiconductor.T he upconversion efficiency resembles that of comparable systems in solution, which we attribute to the large amount of interfaces present in this solid-state film. We anticipate that this synthetic strategy has great prospects for increasing the open-circuit voltage in PbS nanocrystal-based solar cells.
As ub-monolayer CdS shell on PbS quantum dots (QDs) enhances triplet energy transfer (TET) by suppressing competitive charge transfer from QDs to molecules.T he CdS shell increases the linear photon upconversion quantum yield (QY) from 3.5 %f or PbS QDs to 5.0 %f or PbS/CdS QDs when functionalizedw ith at etracene acceptor, 5-CT.W hile transient absorption spectroscopyr eveals that both PbS and PbS/CdS QDs show the formation of the 5-CT triplet (with rates of 5.91 AE 0.60 ns À1 and 1.03 AE 0.09 ns À1 respectively), ultrafast hole transfer occurs only from PbS QDs to 5-CT. Although the CdS shell decreases the TET rate,i te nhances TET efficiency from 60.3 AE 6.1 %to71.8 AE 6.2 %bysuppressing hole transfer.F urthermore,t he CdS shell prolongs the lifetime of the 5-CT triplet and thus enhances TET from 5-CT to the rubrene emitter,further bolstering the upconverison QY.
We report a modular synthetic strategy for accessing heteroatom‐containing polycyclic aromatic hydrocarbons (PAHs). Our approach relies on the controlled generation of transient heterocyclic alkynes and arynes. The strained intermediates undergo in situ trapping with readily accessible oxadiazinones. Four sequential pericyclic reactions occur, namely two Diels–Alder/retro‐Diels–Alder sequences, which can be performed in a stepwise or one‐pot fashion to assemble four new carbon–carbon (C−C) bonds. These studies underscore how the use of heterocyclic strained intermediates can be harnessed for the preparation of new organic materials.
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