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An alternative string theory: The current‐versus‐potential behavior of metal atom strings (Ni, Co, Cr) is dependent on the strength of the d‐orbital coupling along the metal atom chain. Penta‐ and heptachromium strings each exhibit two sets of primary I–V curves, which depend on whether the CrCr bonds alternate and are localized, or are delocalized (see picture).

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A record high PCE of up to 3.2% demonstrates that the efficiency of hybrid solar cells (HSCs) can be boosted by utilizing a unique mono-aniline end group of PSBTBT-NH(2) as a strong anchor to attach to CdTe nanocrystal surfaces and by simultaneously exploiting benzene-1,3-dithiol solvent-vapor annealing to improve the charge separation at the donor/acceptor interface, which leads to efficient charge transportation in the HSCs.

Linear metal string complexes of [M n L 4 (NCS) 2 ] (Scheme 1, M ) Ni II , Co II , or Cr II ; n ) 3 or 5; L ) dpaor tpda 2where dpais dipyridylamido anion and tpda 2is tripyridyldiamido dianion) are studied for the fundamental understanding of the effect of inter-nuclei interactions on electron transfer (ET). The metal strings are isolated within n-alkanethiol monolayers and the properties of ET through various metal strings are differentiated by scanning tunneling microscopy. Although very similar in physical dimension, their apparent heights against the same alkanethiol background are significantly different. The discrepancy is ascribed to electron localization-delocalization among the metal centers.

Two new linear pentanickel complexes [Ni5(bna)4(Cl)2][PF6]2 (1) and [Ni5(bna)4(Cl)2][PF6]4 (2; bna=binaphthyridylamide), were synthesized and structurally characterized. A derivative of 1, [Ni5(bna)4(NCS)2][NCS]2 (3), was also isolated for the purpose of the conductance experiments carried out in comparison with [Ni5(tpda)4(NCS)2] (4; tpda=tripyridyldiamide). The metal framework of complex 2 is a standard [Ni5]10+ core, isoelectronic with that of [Ni5(tpda)4Cl2] (5). Also as in 5, complex 2 has an antiferromagnetic ground state (J=-15.86 cm(-1)) resulting from a coupling between the terminal nickel atoms, both in high-spin sate (S=1). Complex 1 displays the first characterized linear nickel framework in which the usual sequence of NiII atoms has been reduced by two electrons. Each dinickel unit attached to the naphthyridyl moieties is assumed to undergo a one-electron reduction, whereas the central nickel formally remains NiII. DFT calculations suggest that the metal framework of the mixed-valence complex 1 should be described as intermediate between a localized picture corresponding to NiII-NiI-NiII-NiI-NiII and a fully delocalized model represented as (Ni2)3+-NiII-(Ni2)3+. Assuming the latter model, the ground state of 1 results from an antiferromagnetic coupling (J=-34.03 cm(-1)) between the two (Ni2)3+ fragments, considered each as a single magnetic centre (S=3/2). An intervalence charge-transfer band is observed in the NIR spectrum of 1 at 1186 nm, suggesting, in accordance with DFT calculations, that 1 should be assigned to Robin-Day class II of mixed-valent complexes. Scanning tunnelling microscopy (STM) methodology was used to assess the conductance of single molecules of 3 and 4. Compound 3 was found approximately 40% more conductive than 4, a result that could be assigned to the electron mobility induced by mixed-valency in the naphthyridyl fragments.

In this work, we demonstrate that carbon dots (CDs) can be used as a dispersing agent for graphene as well as a reducing agent for KMnO4 for the synthesis of manganese oxide (MnO x )–graphene hybrid nanocomposites for supercapacitor applications. CDs obtained from the pyrolysis of ammonium citrate under dry heating possess excellent solubility in water due to their oxygen- and nitrogen-containing functional groups. In addition, the sp2-carbon-rich CDs exhibited strong interaction with graphene through π–π stacking for self-immobilizing on graphene in the preparation of water-soluble CD/graphene nanocomposites (CDGs). Interestingly, MnO x could be grown in situ on CDGs after reaction with KMnO4 in aqueous solution under a mild reaction temperature (75 °C). Under the mild reaction conditions, CDs undergo sacrificial oxidation for the formation of MnO x nanoparticles on graphene, whereas the graphene’s graphitic carbons are protected. The as-formed nanostructured MnO x on CDGs (MnO x –CDGs) was employed to fabricate flexible solid-state supercapacitor which exhibited good capacitance properties (specific capacitance ∼280 F g–1) with very high charge–discharge cyclic stability (>10 000 cycles) and good capacitance retention at 90° bending angle. Compared to other graphene-based nanocomposites, our one-pot synthesis route for MnO x –CDGs is relatively green, simple, rapid, and cost-effective and has a great potential for the synthesis of different metal oxide-decorated graphene nanocomposites for energy conversion and storage applications

bulk heterojunction (BHJ) confi guration has been attracting considerable interest due to their low-cost fabrication, mechanical fl exibility and potential to provide effi cient conversion of solar energy. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] There are a number of challenges on the way to achieve high power conversion effi ciency (PCE) of solar cells. These include the development of low bandgap conjugated polymers with respect to broad light absorption and effi cient charge separation/transportation via controlling the nanostructure of active layer. As a result, several highly effi cient polymers have been reported with high PCE surpassing than 7% to date. [7][8][9] Considering the power conversion processes, including solar light absorption, exciton generation, exciton dissociation, and charge carriers transport, all occur in the active layers. [17][18][19][20][21][22][23][24][25] Therefore, gaining insight into the nanostructure of the active layer and the corresponding morphology, [22][23][24][25] as well as the photovoltaic mechanism, [17][18][19][20][21] is benefi cial to meliorate the PCE of the resulting BHJ solar cells. It is well known that reducing recombination is a linchpin of increasing device effi ciency. [ 22 ] Therefore, decreasing the thickness of the active layer and maximizing its absorption capability to reduce the device resistance and the probability of charge recombination play key roles to improve the device's PCE. From this viewpoint, a remarkable amount of work has been devoted to utilizing metal nanoparticles (NPs) strategies that result from their localized surface plasmon resonance (LSPR) for effi cient light trapping in the active layer in an aim to enhance photon absorption without the need for a thick fi lm. [26][27][28] To date, most studies are focused on single-composition of gold, silver, and copper NPs, which are almost exclusively suspended in aqueous solution. [28][29][30] In comparison, much less systematic experimental study of alloying metal NPs has been performed in photo voltaic performance so far. [ 31 ] More importantly, conjugated polymers are soluble primarily in organic solvents, which are incompatible with aqueous media. This limits the use of these metal NPs in organic photovoltaic devices. Although many of the device geometries have been reported to directly introduce various species of aqueous phase metal NPs in poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) A one-pot synthesis of large size and high quality AuAg alloy nanoparticles (NPs) with well controlled compositions via hot organic media is demonstrated. Amid the synthesis, complexation between trioctylphosphine (TOP) and metal precursors is found, which slows down the rate of nucleation and leads to the growth of large-size AuAg nanoalloys. The wavelength and relative intensities of the resulting plasmon bands are readily fi ne-tuned during the synthetic process using different Au/Ag precursors molar ratios. In the polymer solar cells, a key step in achieving high effi ciency...