Thermal poling is a widely used method for creating glass surfaces with modified structure and altered properties by application of DC voltage. The mechanism of structural change has remained controversial, especially as poling is performed well below the glass transition temperature. Specifically, the role of Joule heating in facilitating structural transformation has remained an open question, conceivably through local heating to temperatures approaching
- Award ID(s):
- 2133373
- NSF-PAR ID:
- 10528353
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 15
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract T g. Here, we investigate this possibility directly by in situ measurements of the local glass temperature during poling using infrared imaging. Examination near the anode region reveals only a slight temperature increase (~10°C) above the furnace temperature at the start of poling, and remains a few hundred degrees belowT gthroughout. SIMS analysis revealed a ~1‐µm thick alkali depletion layer next to the anode. XPS analysis of the anode, cathode, and unpoled regions shows complex changes in structure and composition including migration of alkali ions, injection of hydrogen at the anode interface, removal of non‐bridging oxygen, and polymerization of the network via electrolysis. All these changes arise as a result of high electric field (~106 V/cm) produced across the highly resistive depletion layer, and refutes any significant increase in the temperature by Joule heating as the cause of their creation. -
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Abstract Despite recent rapid advances in metal halide perovskites for use in optoelectronics, the fundamental understanding of the electrical‐poling‐induced ion migration, accounting for many unusual attributes and thus performance in perovskite‐based devices, remain comparatively elusive. Herein, the electrical‐poling‐promoted polarization potential is reported for rendering hybrid organic–inorganic perovskite photodetectors with high photocurrent and fast response time, displaying a tenfold enhancement in the photocurrent and a twofold decrease in the response time after an external electric field poling. First, a robust meniscus‐assisted solution‐printing strategy is employed to facilitate the oriented perovskite crystals over a large area. Subsequently, the electrical poling invokes the ion migration within perovskite crystals, thus inducing a polarization potential, as substantiated by the surface potential change assessed by Kelvin probe force microscopy. Such electrical‐poling‐induced polarization potential is responsible for the markedly enhanced photocurrent and largely shortened response time. This work presents new insights into the electrical‐poling‐triggered ion migration and, in turn, polarization potential as well as into the implication of the latter for optoelectronic devices with greater performance. As such, the utilization of ion‐migration‐produced polarization potential may represent an important endeavor toward a wide range of high‐performance perovskite‐based photodetectors, solar cells, transistors, scintillators, etc.
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Periodically poled second-order nonlinear materials with submicrometer periods are important for the development of quasi-phase matched backward-wave nonlinear optical processes. Interactions involving counter-propagating waves exhibit many unique properties and enable devices such as backward second harmonic generators, mirrorless optical parametric oscillators, and narrow-band quantum entangled photon sources. Fabrication of dense ferroelectric domain gratings in lithium niobate remains challenging, however, due to lateral domain spreading and merging. Here, we report submicrometer periodic poling of ion-sliced x-cut magnesium oxide doped lithium niobate thin films. Electric-field poling is performed using multiple bipolar preconditioning pulses that improve the poling yield and domain uniformity. The internal field is found to decrease with each preconditioning poling cycle. The poled domains are characterized by piezoresponse force microscopy. A fundamental period of 747 nm is achieved.
