In synthetic metals, free radicals in neutral organic semiconductors are acknowledged as their defects or impurities. However, polycyclic aromatic hydrocarbons (PAHs) with singlet open-shell diradical ground state encourage us to investigate the other potential origin of radicals in neutral organic semiconductors. Herein, for the first time, we observed strong electron spin resonance (ESR) signal in a serials of typical small molecule (SMs). Neutral SMs (NSMs) with strong acceptors including benzothiadiazole, diketopyrrolopyrrole, and naphthalene diimide showed significant ESR signals while they contained strong donors. From the unexpected 1 H NMR broadening and increase of ESR signal, we propose TPA-DPP has singlet open-shell ground state and thermally populated triplet species excited via rising temperature, which represent our new viewpoints different from previous reports. The intensity of the ESR signals and singlet−triplet energy gap of the NSMs are related to their electronic delocalization effect and energy band gap. Moreover, significant ESR spectra were also detected in neutral conjugated polymers, e.g., PCDTBT, P3HT, PTB7, and PffBT4T-2OD. We speculate the open-shell quinoid-radical resonance structure may acts as one of the potential origin of the universal ESR signals of organic semiconductors. This study provides a novel perspective to understand the structure−radical−property relationship of organic semiconductors.

We report a heterometallic seed-mediated synthesis method for monodisperse penta-twinned Cu nanorods using Au nanocrystals as seeds. Elemental analyses indicate that resultant nanorods consist predominantly of copper with a gold content typically below 3 atom %. The nanorod aspect ratio can be readily adjusted from 2.8 to 13.1 by varying the molar ratio between Au seeds and Cu precursor, resulting in narrow longitudinal plasmon resonances tunable from 762 to 2201 nm. Studies of reaction intermediates reveal that symmetry-breaking is promoted by rapid nanoscale diffusion in Au−Cu alloys and the formation of a goldrich surface. The growth pathway features coevolving shape and composition whereby nanocrystals become progressively enriched with Cu concomitant with nanorod growth. The availability of uniform colloidal Cu nanorods with widely tunable aspect ratios opens new avenues toward the synthesis of derivative onedimensional metal nanostructures, and applications in surface-enhanced spectroscopy, bioimaging, and electrocatalysis, among others.

Symmetric-breaking strategy has broadly applied in organic photovoltaic material design while a comprehensive understanding of the effects of two dimension (2D) asymmetric side chains in all-small-molecule organic solar cells (ASM-OSCs)...

The decomposition of methanol on Pt nanoclusters grown from vapor deposition onto an ordered Al 2 O 3 / NiAl(100) thin film was investigated under ultrahigh vacuum conditions with various surface probe techniques. The Pt clusters had mean diameter near 2.3 nm and height 0.4 nm before their coalescence; consisting of phase fcc, the clusters grew with their facets either ( 111) or ( 001) parallel to the θ-Al 2 O 3 (100) surface, depending on the temperature of growth. More than half the adsorbed monolayer of methanol on the Pt clusters decomposed via two channels: dehydrogenation to CO and C−O bond scission. The dehydrogenation was dominant and induced first at low-coordinated Pt sites, at 150 K on Pt(001) clusters and 200 K on Pt(111) clusters, whereas both lowcoordinated and some terrace Pt sites exhibited reactivity, despite the cluster size. On average, one CO was produced per surface Pt site, for a monolayer of methanol on either Pt(111) or Pt(001) clusters. In the other reaction, scission of the C−O bond occurred primarily in methanol itself and began about 250 K; the intermediate methyl preferentially formed methane on combining with atomic H from dehydrogenated methanol. No preferential reaction site for the C−O bond scission is indicated, but this process showed a remarkable dependence on the size and lattice parameter of the clusters: the probability of C−O bond scission decreased when the size increased and the lattice parameter decreased.

Unconventional fluorescence emission of non-conjugated lignin-SAF (GSL) was reported and GSL-doped PEDOT showed high performance in organic electronics.