Efficient Photovoltaic Current Generation at Ferroelectric Domain Walls

Seidel, Jan; Fu, Deyi; Yang, So Young; Alarcón-Lladó, Esther; Wu, Junqiao; Ramesh, R.; Ager, Joel W.

doi:10.1103/physrevlett.107.126805

Cited by 372 publications

(327 citation statements)

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“…In general, the spatial extent of spontaneous polarization vectors in ferroelectric crystals is typically manifested as domains (typically spanning over a few mm in size) and domain walls (DW, 1-2 nm in width), which must intimately determine the polarization-switching characteristics in a ferroelectric continuum. [1][2][3][4][8][9][10] In this study, we demonstrate a single-domain photovoltaic switch based on a lateral BFO channel with voltage pulses, in which coherent switching is achieved on a time scale as fast as 10 ms. By employing spatially and spectrally resolved I ph imaging on a single domain, we provide direct evidence that the photovoltaic switching characteristics are determined by the internal polarization vector along the applied electrical field (E-field). In addition, in multidomain channels, we show that oxygen vacancy accumulation at the domain walls (DWs), characteristic of perovskite oxides, is intimately associated with the diffusive switching characteristics.…”

Section: Introductionmentioning

confidence: 99%

Single ferroelectric-domain photovoltaic switch based on lateral BiFeO3 cells

Sung

Lee

et al. 2013

NPG Asia Mater

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The bistability of ferroelectric polarization states serves as a basis for solid-state memory. This phenomenon can also yield an interesting photovoltaic effect in such a way that the directional photocarrier motion follows the inherent potential gradient imposed by the ferroelectric polarization vectors. Here, we demonstrate a single-domain photovoltaic switch based on lateral BiFeO 3 channels, in which such photovoltaic switching is achieved by a coherent single-domain reversal with a short electrical pulse. We then provide visual evidence for such operations with a series of spatially and spectrally resolved short-circuit photocurrent images. Specifically, we reveal that the sequential photovoltaic current images directly reflect the remanent polarization states of a single-domain channel. We also verify that, in multidomain channels, diffusive switching characteristics are determined not only by the internal polarization vector within the domain but also by oxygen vacancy accumulation at the domain walls. Keywords: ferroelectrics; multiferroics; oxide photonics; photovoltaics INTRODUCTIONHomogeneous light illumination on non-centrosymmetric crystals, such as ferroelectrics, in the intrinsic absorption range can give rise to an interesting photovoltaic effect, dubbed as the bulk photovoltaic effect. 1,2 This effect is distinct from that of typical semiconductor p-n junction photovoltaics and excitonic heterojunction photovoltaics in that the photogenerated carriers can be separated along the inherent polar directions, ensuing the unidirectional photocurrent (I ph ) and photovoltage (V ph ), associated with the spontaneous ferroelectric polarization vector (P s ). Therein, the open-circuit voltage (V oc ) is determined by the magnitude of the remanent polarization of ferroelectrics, and it can be additively as large as a few hundreds of volts, although the short-circuit current (I sc I ph at 0 V) is low due to the insulating character of the system. This phenomenon has been recently revisited with a small band-gap, BiFeO 3 (BFO) ferroelectric, from which a substantially higher photon-to-charge generation efficiency can be achieved in the visible range compared with that of other insulating ferroelectrics. [3][4][5][6][7][8] reported that diodelike rectification follows the polarization-dependent interface bandbending of BFO single-crystal slabs that are electrically switchable, that is, V oc and I sc are defined by the remanent polarization directions. In general, the spatial extent of spontaneous polarization vectors in ferroelectric crystals is typically manifested as domains (typically spanning over a few mm in size) and domain walls (DW, 1-2 nm in

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Section: Introductionmentioning

confidence: 99%

Single ferroelectric-domain photovoltaic switch based on lateral BiFeO3 cells

Sung

Lee

et al. 2013

NPG Asia Mater

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“…Despite this, much attention has been paid to ferroelectric memory devices 1,2 , which are based on the binary conduction states caused by the ferroelectric polarization switching. Recent work 3 indicates that strong electric fields existing at ferroelectric domain walls (2 nm) can separate photo-induced charges in BiFeO 3 (ref. 4) with a low internal quantum efficiency (B10%), and the sawtooth-like potential developed inside the device is responsible for an above-band gap photovoltage [5][6][7] .…”

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confidence: 99%

Storage of an electric field for photocurrent generation in ferroelectric-functionalized organic devices

Dalgleish

Matsushita

et al. 2014

Nat Commun

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Organic optoelectronic devices are usually driven by the electric field generated from an electrode potential difference or bias voltage. Although poled ferroelectric domains may produce oriented stray fields, few efforts have been made to utilize them for photocurrent generation in organic devices. Here we show that large net fields caused by incomplete screening during ferroelectric polarization, and which can be 'restored' by short voltage pulses, can facilitate exciton dissociation in organic semiconductors. The oriented fields, comparable with that produced by an electrode potential difference (1B10 MV m À 1 ), here are found to be responsible for the photocurrent in our devices. A prototype for an organic photodetector driven by such stray fields is demonstrated. The photoresponsivity, without any optimization, can achieve B0.1 mA W À 1 . This study provides a different operation principle for the generation of photocurrent in organic optoelectronic devices. Furthermore, the polarity-tunable photoresponse may lead to new photoresponsive memory devices.

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“…Physical model based on complex domains and domain walls of epitaxial BFO thin films are presented elsewhere. 21,28 In polycrystalline ferroelectric films/ceramics, photo current has been characterized to series connections of different grains/grain boundaries or domains/ domain walls. 29 The conducting domain walls become more semiconducting or insulating with increase in temperature which may reduce the charge generation near the interface.…”

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confidence: 99%