DJL

Charge transfer and interactions at organic heterojunctions (OHJs) are known to have critical influences on various properties of organic electronic devices. In this Research News article, a short review is given from the electronic viewpoint on how the local molecular interactions and interfacial energetics at P/N OHJs contribute to the recombination/dissociation of electron-hole pairs. Very often, the P-type materials donate electrons to the N-type materials, giving rise to charge-transfer complexes (CTCs) with a P^δ+–N^δ− configuration. A recently observed opposite charge-transfer direction in OHJs is also discussed (i.e., N-type material donates electrons to P-type material to form P^δ−–N^δ+). Recent studies on the electronic structures of CTC-forming material pairs are also summarized. The formation of P^δ−–N^δ+-type CTCs and their correlations with exciplex emission are examined. Furthermore, the potential applications of CTCs in NIR photovoltaic devices are reviewed.

Local molecular interactions and interfacial energetics at organic P/N junctions contribute to their role in the recombination/dissociation of electron-hole pairs. Recent accomplishments regarding the electronic structures of charge-transfer-complex-forming material pairs and their role in exciplex emission and near-IR photo­charge generation using wide-energy-gap semiconductors are highlighted.

Experimental results of the direct deposition of graphene films on gallium nitride (GaN)/sapphire substrates by catalyst-free, atmospheric pressure CVD are presented. The quality and thickness of the synthesized samples can be controlled by the growth conditions. The Raman mappings are reported. The measured optical transparency and electrical transport show promising potential for the application of graphene/GaN compounds in microelectronics and optoelectronics.

Herein, we investigate human single hydroxyapatite crystals (enamel and dentine) by convergent-beam electron diffraction (CBED) and automated electron-diffraction tomography (ADT). The CBED pattern shows the absence of the mirror plane perpendicular to the c axis leading to the P6₃ space group instead of the P6₃/m space group considered for larger-scale crystals, this is confirmed by ADT. This experimental evidence is of prime importance for understanding the morphogenesis and the architectural organization of calcified tissues.

Human single hydroxyapatite crystals (enamel and dentine; see figure) were investigated by convergent-beam electron diffraction (CBED) and automated electron-diffraction tomography (ADT). The CBED pattern shows the absence of the mirror plane perpendicular to the c axis leading to the P6₃ space group instead of the P6₃/m space group considered for larger-scale crystals. This is confirmed by ADT. This experimental evidence is of prime importance for understanding the morphogenesis and the architectural organization of calcified tissues.

Gravure printing of graphene is demonstrated for the rapid production of conductive patterns on flexible substrates. Development of suitable inks and printing parameters enables the fabrication of patterns with a resolution down to 30 μm. A mild annealing step yields conductive lines with high reliability and uniformity, providing an efficient method for the integration of graphene into large-area printed and flexible electronics.