Non-local photocurrent in a ferroelectric semiconductor SbSI under local photoexcitation

Nakamura, Masao; Hatada, Hiroki; Ogawa, Norio; Sotome, M.; Tokura, Y.; Kawasaki, Masashi

doi:10.1063/5.0001524

Cited by 10 publications

(9 citation statements)

References 22 publications

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“…x = ±200 corresponds to the case in which the light position is at the ends of the chain, and x = 0 is when the light is at the center. Unlike the case in the clean limit (26)(27)(28)35), the current decays when the light position goes away from the two ends. Fig.…”

Section: Resultsmentioning

confidence: 79%

Theory of bulk photovoltaic effect in Anderson insulator

Ishizuka

Nagaosa

2021

Proc. Natl. Acad. Sci. U.S.A.

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The localization of wavefunction by disorder makes a conductive material an insulator with vanishing conductivity at zero temperature. A similar outcome is expected for the photocurrent in semiconductor p-n junctions because the photoexcited carriers cannot drift through the device. In contrast, we here show numerically that the bulk photovoltaic effect—the photovoltaic effect in noncentrosymmetric bulk materials—occurs in a noncentrosymmetric, disordered, one-dimensional insulator where all eigenstates are localized. We find this photocurrent remains, even when the energy scale of random potential is larger than the bandwidth. On the other hand, the photocurrent decays exponentially when the excitation is local, i.e., when only a part of the device is illuminated. The photocurrent also vanishes if the relaxation occurs only by contact with the electrodes. Our result implies that the ratio of the photovoltaic current and the direct current by the variable-range hopping increases with decreasing temperature. These results suggest a route to design high-efficiency solar cells and photodetectors.

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Section: Resultsmentioning

confidence: 79%

Theory of bulk photovoltaic effect in Anderson insulator

Ishizuka

Nagaosa

2021

Proc. Natl. Acad. Sci. U.S.A.

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“…The only positive pyroelectric response of the SbSI–TiO 2 nanogenerator is observed ( Figure 5 b,d) due to the fact that the rectifying p – n heterojunction was formed between the SbSI nanowires and the ITO electrode as well between the SbSI nanowires and the TiO 2 nanoparticles. Usually, SbSI is regarded as p -type semiconductor [ 31 , 37 , 61 , 71 , 72 ], whereas both ITO [ 73 ] and TiO 2 [ 74 ] exhibit n -type electrical conductivity. The work functions of ITO, TiO 2 , and SbSI were 4.4–4.5 eV [ 75 ], 4.2–4.7 eV [ 76 ], and 5 eV [ 31 , 71 , 72 ], respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Usually, SbSI is regarded as p -type semiconductor [ 31 , 37 , 61 , 71 , 72 ], whereas both ITO [ 73 ] and TiO 2 [ 74 ] exhibit n -type electrical conductivity. The work functions of ITO, TiO 2 , and SbSI were 4.4–4.5 eV [ 75 ], 4.2–4.7 eV [ 76 ], and 5 eV [ 31 , 71 , 72 ], respectively. Accordingly, since the work function of p -type SbSI is higher than that of n-type ITO and n -type TiO 2 , a built-in electric field was formed in the ITO/SbSI and TiO 2 /SbSI interfaces.…”

Section: Resultsmentioning

confidence: 99%

Pyroelectric Nanogenerator Based on an SbSI–TiO2 Nanocomposite

Mistewicz

2021

Sensors

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For the first time, a composite of ferroelectric antimony sulfoiodide (SbSI) nanowires and non-ferroelectric titanium dioxide (TiO2) nanoparticles was applied as a pyroelectric nanogenerator. SbSI nanowires were fabricated under ultrasonic treatment. Sonochemical synthesis was performed in the presence of TiO2 nanoparticles. The mean lateral dimension da = 68(2) nm and the length La = 2.52(7) µm of the SbSI nanowires were determined. TiO2 nanoparticles served as binders in the synthesized nanocomposite, which allowed for the preparation of dense films via the simple drop-casting method. The SbSI–TiO2 nanocomposite film was sandwiched between gold and indium tin oxide (ITO) electrodes. The Curie temperature of TC = 294(2) K was evaluated and confirmed to be consistent with the data reported in the literature for ferroelectric SbSI. The SbSI–TiO2 device was subjected to periodic thermal fluctuations. The measured pyroelectric signals were highly correlated with the temperature change waveforms. The magnitude of the pyroelectric current was found to be a linear function of the temperature change rate. The high value of the pyroelectric coefficient p = 264(7) nC/(cm2·K) was determined for the SbSI–TiO2 nanocomposite. When the rate of temperature change was equal dT/dt = 62.5 mK/s, the maximum and average surface power densities of the SbSI–TiO2 nanogenerator reached 8.39(2) and 2.57(2) µW/m2, respectively.

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“…The suppression of the Ohmic dc current contributes to the efficiency of solar cells by reducing the current back-flow. For instance, a recent work discusses that the shift current device acts as a current source; the output current reads J out = J s R * /(2R 0 + R * ) where R * and R 0 are respectively the resistivity of the photovoltaic device and the leads [29]. The result implies materials with high R * are beneficial for applications.…”

Section: Disussionmentioning

confidence: 99%

Theory of shift current in Anderson insulator

Ishizuka,

Nagaosa

2020

Preprint

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Shift current is a photovoltaic current in bulk noncentrosymmetric insulator [1][2][3][4][5]. Studies on shift current have so far focused on the extended Bloch waves, such as in semiconductors [4,6] and perovskites [1,7]. In contrast, it is unknown whether the localized wavefunctions support the dc photocurrent. Here, we show theoretically that the dc shift current appears in a noncentrosymmetric disordered one-dimensional insulator with random potential. When the light illuminates the entire sample, the photocurrent forms in presence of the electron-phonon coupling. We find this photocurrent remains robustly even when the energy scale of random potential is larger than the bandwidth. On the other hand, the photocurrent decays exponentially when the excitation is local, or the relaxation is only due to the contact with the electrodes. These results open a route to design high-efficiency solar cells and photodetectors.

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Non-local photocurrent in a ferroelectric semiconductor SbSI under local photoexcitation

Cited by 10 publications

References 22 publications

Theory of bulk photovoltaic effect in Anderson insulator

Theory of bulk photovoltaic effect in Anderson insulator

Pyroelectric Nanogenerator Based on an SbSI–TiO2 Nanocomposite

Theory of shift current in Anderson insulator

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