The semiconducting p-n junction is a simple device structure with great relevance for electronic and optoelectronic applications. The successful integration of low-dimensional materials in electronic circuits has opened the way forward for producing gate-tunable p-n junctions. In that context, we present here an organic (Cu-phthalocyanine)-2D layered material (MoS2) hybrid p-n junction with both gate-tunable diode characteristics and photovoltaic effect. Our proof-of-principle devices show multifunctional properties with diode rectifying factors of up to 10(4), while under light exposure they exhibit photoresponse with a measured external quantum efficiency of ∼11%. As for their photovoltaic properties, we found open circuit voltages of up to 0.6 V and optical-to-electrical power conversion efficiency of 0.7%. The extended catalogue of known organic semiconductors and two-dimensional materials offer the prospect for tailoring the properties and the performance of the resulting devices, making organic-2D p-n junctions promising candidates for future technological applications.

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wileyonlinelibrary.comGraphene, [ 11 ] a one-atom thick zero band gap semiconductor has allowed the development of new electronic device schemes such as the graphene-barristor, [ 12 ] the graphene-vertical-fi eld-effecttransistor (VFET), [13][14][15][16] and the graphenebase hot electron transistor. [ 17 ] In organic electronics, graphene can be an ideal choice to use as the injector (or source) electrode for a VFET since its Fermi level, its corresponding work function and its available low density of states (DOS) [ 18 ] can all be easily modulated, providing a tunable energy barrier which eventually controls the device operation. In addition, the electric fi eld produced by a gate electrode will extend into the organic semiconductor, as the monolayer thickness of graphene is insuffi cient to fully screen it. [ 13,19 ] In order to increase the performance of organic thin fi lm transistors (OTFT) compared with the inorganic counterparts, a unique vertical architecture with a molecular semiconductor (C 60 ) was fi rst demonstrated using a thin and rough (with a roughness comparable to the thickness) metal electrode. [ 20 ] A clear advantage of the vertical over the lateral organic transistor geometry is that the channel length is controlled by the thickness of the organic layer and the devices can be downsized in both the lateral and the vertical directions. In the case of a perforated metallic source electrode, the electric fi eld can directly access the metal/organic interface which causes the energy level realignment (similar to the band bending in inorganic semiconductor) in the organic semiconductor. Although Ma and Yang have reported a large on/off current ratio (≈10 6 ), the high DOS and the fi xed work function of the metallic electrode (injector) limits its application to a few organic semiconductors. [ 20 ] Later on, Liu et al. introduced a carbon nanotube-based source electrode with low DOS in organic VFETs for a wide range of organic semiconductors. [ 21 ] Carbon nanotubes allow new mechanisms for transistor operation such as the tuning of the gate modulated energy barrier. Graphene, similar to carbon nanotubes in its electrical and mechanical properties, has additional advantages over them due to the large-scale availability (chemical vapor deposition (CVD)-grown graphene) of chemically inert high quality 2D surfaces. [ 14,22 ] On the other hand, fullerene (C 60 ) is one of the most widely studied molecular semiconductors [ 2,5,20,[23][24][25] and a common choice as an active media for transistors. C 60 has an energy gap ( E g = 1.7 eV), between its highest occupied molecular orbital Gate-Controlled Energy Barrier at a Graphene/Molecular Semiconductor JunctionSubir Parui , * Luca Pietrobon , David Ciudad , Saül Vélez , Xiangnan Sun , Fèlix Casanova , Pablo Stoliar , and Luis E. Hueso * The formation of an energy-barrier at a metal/molecular semiconductor junction is a universal phenomenon which limits the performance of many molecular semiconductor-based electronic devices, from fi eld-effect trans...

Chemically engineered interfaces are shown to produce inversions of the magnetoresistance in spintronic devices including lithium fluoride interlayers. This behavior is explained by the formation of anti-ferromagnetic difluoride layers. By changing the order of deposition of the different materials, the sign of the magnetoresistance can be deterministically controlled both in organic spin valves and in inorganic magnetic tunnel junctions.

Hole-doping into the Mott insulator LaMnO3 results in a very rich magneto-electric phase diagram, including colossal magnetoresistance and different types of charge and orbital ordering. On the other hand, LaMnO3 presents an important catalytic activity for oxygen reduction, which is fundamental for increasing the efficiency of solid-oxide fuel cells and other energy-conversion devices. In this work, we report the chemical solution (water-based) synthesis of high-quality epitaxial thin films of LaMnO3, free of defects at square-centimeter scales, and compatible with standard microfabrication techniques. The films show a robust ferromagnetic moment and large magnetoresistance at room temperature. Through a comparison with films grown by pulsed laser deposition, we show that the quasi-equilibrium growth conditions characteristic of this chemical process can be exploited to tune new functionalities of the material.