Recent advances in organic spin response include long polaron spin-coherence times measured by optically detected magnetic resonance (ODMR), substantive room-temperature magnetoelectroluminescence and magnetoconductance obtained in organic light-emitting diodes (OLEDs) and spin-polarized carrier injection from ferromagnetic electrodes in organic spin valves (OSVs). Although the hyperfine interaction (HFI) has been foreseen to have an important role in organic spin response, no clear experimental evidence has been reported so far. Using the chemical versatility advantage of the organics, we studied and compared spin responses in films, OLED and OSV devices based on pi-conjugated polymers made of protonated, H-, and deuterated, D-hydrogen having a weaker HFI strength. We demonstrate that the HFI does indeed have a crucial role in all three spin responses. OLED films based on the D-polymers show substantially narrower magneto-electroluminescence and ODMR responses, and as a result of the longer spin diffusion obtained, OSV devices based on D-polymers show a substantially larger magnetoresistance.

This paper proposes a double-sided LCC compensation network and its tuning method for wireless power transfer (WPT). With the proposed topology and its tuning method, the resonant frequency is irrelevant with the coupling coefficient between the two coils and is also independent of the load condition, which means that the system can work at a constant switching frequency. Analysis in frequency domain is given to show the characteristics of the proposed method. We also propose a method to tune the network to realize zero voltage switching (ZVS) for the Primary-side switches. Simulation and experimental results verified analysis and validity of the proposed compensation network and the tuning method. A wireless charging system with output power of up to 7.7 kW for electric vehicles was built, and 96% efficiency from dc power source to battery load is achieved.

We explore the possibility that hyperfine interaction causes the recently discovered organic magnetoresistance (OMAR) effect. Our study employs both experiment and theoretical modelling. An excitonic pair mechanism model based on hyperfine interaction, previously suggested by others to explain magnetic field effects in organics, is examined. Whereas this model can explain a few key aspects of the experimental data, we, however, uncover several fundamental contradictions as well. By varying the injection efficiency for minority carriers in the devices, we show experimentally that OMAR is only weakly dependent on the ratio between excitons formed and carriers injected, likely excluding any excitonic effect as the origin of OMAR.Comment: 10 pages, 7 figures, 1 tabl

The spin-polarized organic light-emitting diode (spin-OLED) has been a long-sought device within the field of organic spintronics. We designed, fabricated, and studied a spin-OLED with ferromagnetic electrodes that acts as a bipolar organic spin valve (OSV), based on a deuterated derivative of poly(phenylene-vinylene) with small hyperfine interaction. In the double-injection limit, the device shows ~1% spin valve magneto-electroluminescence (MEL) response, which follows the ferromagnetic electrode coercive fields and originates from the bipolar spin-polarized space charge-limited current. In stark contrast to the response properties of homopolar OSV devices, the MEL response in the double-injection device is practically independent of bias voltage, and its temperature dependence follows that of the ferromagnetic electrode magnetization. Our findings provide a pathway for organic displays controlled by external magnetic fields.

We measured magnetoconductance (MC) response in a number of unipolar and bipolar organic diodes based on π-conjugated polymers and small molecules at fields |B|<100  mT and various bias voltages and temperatures. Similar to magneto-electroluminescence, the MC(B) response in bipolar diodes shows a sign reversal at ultrasmall |B|<1-2  mT due to interplay of hyperfine and Zeeman interactions in opposite-charge polaron pairs. Surprisingly, similar MC(B) response was also measured in unipolar devices, indicating the existence of like-charge polaron pairs, however, with a clear difference between the hyperfine interaction constants of electron polaron and hole polaron.

accelerated impressively and advanced to a range of materials and a number of techniques to verify the successful injection and transport of the SP carriers. [ 1,2,10,11 ] The effect has been realized in a variety of materials combinations such as FM fi lms, FM/anti-FM coupled layers, or FM semiconductors as the injection/detection electrodes and the metals, superconductors, inorganic semiconductors, organic semiconductors, and insulators including ferroelectric and topological insulators as the spacers. [ 1,2,[12][13][14][15][16][17][18] The GMR effect was extensively studied using non-magnetic metallic interlayer and its applications such as electric switching, magnetic recording, and sensors were suggested and employed. [ 1,2,16 ] However, all-metallic spintronic devices imposed restrictions in applications as they are characterized by short spin relaxation time (≈picosecond) and are not suitable for coherent spin manipulation. [ 1,2,19 ] To overcome these limitations, the spintronics community caught its attention towards hybrid devices with semiconductors (SCs) sandwiched in between the FM layers and continued advancing to a range of semiconducting materials. [ 2,14,[20][21][22] The organic semiconductors (OSCs) are among the youngest members of the spacer materials and were fi rst tested in the spintronic devices only about a decade ago. Nevertheless, OSC devices have been of continuously advancing research topics over the past three decades for their rich physics, fl exible chemi stry, cost effi ciency, and potential applications in new generations of electronic devices including organic light emitting diodes (OLEDs), [23][24][25] organic solar cells, [ 26,27 ] and organic fi eld effect transistor. [ 28,29 ] In fact, OLEDs have already revolutionized the modern display industry and spin-dependent devices such as organic spin valves (OSVs), OLED-based magnetic sensors, and spin-OLEDs are under intensive study to achieve their new avenues. [30][31][32] This increasing interest on organic electronics is for their several distinctions over inorganic counterparts. [19][20][21]33,34 ] Electronically, the band theory explains the electric transport in inorganic SCs while charge hopping is the main transport mechanism in the OSCs with much smaller carrier mobility. This is a favorable condition for large electron-hole pair recombination without the need of using a p-n junction structure. [23][24][25] Spintronically, the inorganic SCs contain heavy atoms giving rise to a large spin-orbit coupling (SOC), which is a response of the electron spin degree of freedom to its orbital environment. The strength of the SOC in solids depends upon the nature of orbital wave functions of electrons and the materials structure. [ 35 ] In case of hydrogenic wave-function-like electrons (s-orbital electrons), it is Organic spintronics is an emerging and potential platform for future electronic devices. Signifi cant progress has been made in understanding the spin injection, manipulation, and detection in organic spin valves in the p...

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