Isotope effect in spin response of pi-conjugated polymer films and devices.
TL;DR: It is demonstrated that the HFI does indeed have a crucial role in all three spin responses and OLED films based on the D-polymers show substantially narrower magneto-electroluminescence and ODMR responses, and OSV devices based on D- polymers show a substantially larger magnetoresistance.
Abstract: The origin of the effect that a magnetic field has on various electronic properties of organic semiconductors is still controversial. It is now shown that substituting hydrogen for deuterium in conducting polymers changes the response to a magnetic field substantially, proving the essential part played by hyperfine interaction in this effect.
Citations
More filters
TL;DR: The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials and highlights the capabilities of various experimental techniques for characterization, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field.
Abstract: Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjug...
995 citations
TL;DR: In this paper, the authors provide a basic physical description of the exciton diffusion in organic semiconductors and present experimental methods that are used to measure the key parameters of this process.
Abstract: The purpose of this review is to provide a basic physical description of the exciton diffusion in organic semiconductors. Furthermore, experimental methods that are used to measure the key parameters of this process as well as strategies to manipulate the exciton diffusion length are summarized. Special attention is devoted to the temperature dependence of exciton diffusion and its relationship to Forster energy transfer rates. An extensive table of more than a hundred measurements of the exciton diffusion length in various organic semiconductors is presented. Finally, an outlook of remaining challenges for future research is provided.
659 citations
TL;DR: Advances in the application of hydrogen isotopes in the life sciences are described and 3 H, in particular, has seen an increase in utilization, especially in pharmaceutical drug discovery.
Abstract: Hydrogen isotopes are unique tools for identifying and understanding biological and chemical processes. Hydrogen isotope labelling allows for the traceless and direct incorporation of an additional mass or radioactive tag into an organic molecule with almost no changes in its chemical structure, physical properties, or biological activity. Using deuterium-labelled isotopologues to study the unique mass-spectrometric patterns generated from mixtures of biologically relevant molecules drastically simplifies analysis. Such methods are now providing unprecedented levels of insight in a wide and continuously growing range of applications in the life sciences and beyond. Tritium (3 H), in particular, has seen an increase in utilization, especially in pharmaceutical drug discovery. The efforts and costs associated with the synthesis of labelled compounds are more than compensated for by the enhanced molecular sensitivity during analysis and the high reliability of the data obtained. In this Review, advances in the application of hydrogen isotopes in the life sciences are described.
394 citations
TL;DR: In this article, hydrogen adatoms were used to generate magnetic moments inside single layer graphene. But the magnetic moment formation appeared only after hydrogen adatsoms were introduced to the graph.
Abstract: Hydrogen adatoms are shown to generate magnetic moments inside single layer graphene. Spin transport measurements on graphene spin valves exhibit a dip in the nonlocal spin signal as a function of the applied magnetic field, which is due to scattering (relaxation) of pure spin currents by exchange coupling to the magnetic moments. Furthermore, Hanle spin precession measurements indicate the presence of an exchange field generated by the magnetic moments. The entire experiment including spin transport is performed in an ultrahigh vacuum chamber, and the characteristic signatures of magnetic moment formation appear only after hydrogen adatoms are introduced. Lattice vacancies also demonstrate similar behavior indicating that the magnetic moment formation originates from ${p}_{z}$-orbital defects.
248 citations
TL;DR: In this article, the observation of magnetic field effects in hybrid perovskites may help to explain their high efficiencies, but the mechanisms responsible for their performance are not clear yet.
Abstract: Perovskite photovoltaics are the fastest-advancing solar technology but the mechanisms responsible for their performance are not clear. The observation of magnetic field effects in hybrid perovskites may help to explain their high efficiencies.
218 citations
References
More filters
TL;DR: In this article, the mean magnetizations of the two ferromagnetic film are parrallel or antiparallel and conductance measurement is related to the spin polarizations of conduction electrons.
3,365 citations
TL;DR: The observation of spin transport, as well as Larmor spin precession, over micrometre-scale distances in single graphene layers is reported, indicating that spin coherence extends underneath all of the contacts.
Abstract: Electronic transport in single or a few layers of graphene is the subject of intense interest at present. The specific band structure of graphene, with its unique valley structure and Dirac neutrality point separating hole states from electron states, has led to the observation of new electronic transport phenomena such as anomalously quantized Hall effects, absence of weak localization and the existence of a minimum conductivity. In addition to dissipative transport, supercurrent transport has also been observed. Graphene might also be a promising material for spintronics and related applications, such as the realization of spin qubits, owing to the low intrinsic spin orbit interaction, as well as the low hyperfine interaction of the electron spins with the carbon nuclei. Here we report the observation of spin transport, as well as Larmor spin precession, over micrometre-scale distances in single graphene layers. The 'non-local' spin valve geometry was used in these experiments, employing four-terminal contact geometries with ferromagnetic cobalt electrodes making contact with the graphene sheet through a thin oxide layer. We observe clear bipolar (changing from positive to negative sign) spin signals that reflect the magnetization direction of all four electrodes, indicating that spin coherence extends underneath all of the contacts. No significant changes in the spin signals occur between 4.2 K, 77 K and room temperature. We extract a spin relaxation length between 1.5 and 2 mum at room temperature, only weakly dependent on charge density. The spin polarization of the ferromagnetic contacts is calculated from the measurements to be around ten per cent.
2,110 citations
TL;DR: The injection, transport and detection of spin-polarized carriers using an organic semiconductor as the spacer layer in a spin-valve structure is reported, yielding low-temperature giant magnetoresistance effects as large as 40 per cent.
Abstract: A spin valve is a layered structure of magnetic and non-magnetic (spacer) materials whose electrical resistance depends on the spin state of electrons passing through the device and so can be controlled by an external magnetic field. The discoveries of giant magnetoresistance and tunnelling magnetoresistance in metallic spin valves have revolutionized applications such as magnetic recording and memory, and launched the new field of spin electronics--'spintronics'. Intense research efforts are now devoted to extending these spin-dependent effects to semiconductor materials. But while there have been noteworthy advances in spin injection and detection using inorganic semiconductors, spin-valve devices with semiconducting spacers have not yet been demonstrated. pi-conjugated organic semiconductors may offer a promising alternative approach to semiconductor spintronics, by virtue of their relatively strong electron-phonon coupling and large spin coherence. Here we report the injection, transport and detection of spin-polarized carriers using an organic semiconductor as the spacer layer in a spin-valve structure, yielding low-temperature giant magnetoresistance effects as large as 40 per cent.
1,298 citations