We report flexible and elastic enough nanofibers with diameters down to 60 nm and lengths up to 500 mm, fabricated by one-step drawing process from molten poly(trimethylene terephthalate) (PTT), exhibiting high surface smoothness and length uniformity. A series of ultracompact devices (such as optical beam splitters, couplers, rings, resonators, and tweezer/scissor-shaped structures) and nanophotonic device arrays have been assembled by the PTT nanofibers. Quantitative studies demonstrate that the PTT nanofibers/nanofiber devices exhibit good guiding properties with low optical loss from visible to near infrared region. The results suggest that the PTT nanophotonic fibers/wires would be promising candidates in constructing miniaturized photonic devices and ultracompact photonic integrated circuits (PICs), and a one-step drawing as an alternative to the standard optical bench technique.
Low-cost wide-bandgap solar cells are attractive candidates for potential applications including tandem photovoltaics, solar-driven electrochemical energetic devices, and photovoltaic solar panels for spacecraft due to their relatively high output voltage and sustainability in critical environment. Recently, solar cells based on the organic-inorganic lead halide perovskites have emerged as a promising avenue toward high power conversion efficiency (PCE). However, the investigations on achieving high operating voltage with sufficient output power remains a missing part for the halide perovskite solar cells. Here the effectiveness of employing both anode and cathode interfacial modification layers to reach high open-circuit voltage (V OC ) for the methylammonium lead tribromide (MAPbBr 3 ) perovskite solar cells is demonstrated. Specifically, high work function e-beam processed MoO x layer with vacuum annealing treatment is used to reengineer the anode interface and an atomic layer deposited ZrO 2 layer is used to modify the cathode interface, respectively. The minimized energy barrier height by MoO x modification and hole-blocking effect by ZrO 2 synergistically restrain the charge carrier recombination loss and render a consequent larger quasi-Fermi level separation that endows a higher V OC . The MAPbBr 3 perovskite solar cell with a highest PCE of 10.08% and a new record V OC of 1653 mV under one sun-illumination are demonstrated.The organic-inorganic lead halide perovskite based photovoltaics have attracted huge attention in the past few years. [1][2][3][4][5] The unique electronic band structures, large dielectric constant, and relatively small effective masses make them optimal candidates for solar cell applications. [6][7][8][9][10] To date, vast research attentions have been driven to the classic prototype methylammonium lead triiodide (MAPbI 3 ) perovskite owning to its benign bandgap of 1.5-1.6 eV [11] that well matches the solar spectra. In contrast, solar cells based on wide-bandgap halide perovskite derivatives such as methylammonium lead tribromide (MAPbBr 3 ) have got less focus for its lower maximum efficiency predicted by Shockley-Queisser theory. [12] Nevertheless, the anticipated higher open-circuit voltage (V OC ) delivered by the wide-bandgap perovskite solar cells is expected to offer great opportunities for various applications including but not limited to solar driven water electrolysis, [13] electrocatalysis [14] and electrochemical energy storage, [15] multijunction solar cells, [16] space solar panels [17] and solar driving electronics for yellow and blue light emitting diode (LED). [18,19] To reach a high V OC and simultaneously maintain a large out-put power, most previous studies have focused on optimizing the perovskite polycrystalline film quality and synthesizing novel electrode buffer-layers. [20][21][22][23][24][25] The advances in techniques of growing high-quality perovskite thin films have revealed the superior electronic properties with carrier diffusion length in order of mi...
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