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Origin of photovoltaic effect in superconducting YBa2Cu3O6.96 ceramics.

Yang F, Han MY, Chang FG - Sci Rep (2015)

Bottom Line: The origin of the potential may be readily associated with the proximity effect at metal-superconductor interface when YBCO is superconducting and its value is estimated to be ~10(-8) mV at 50 K with a laser intensity of 502 mW/cm(2).Combination of a p-type material YBCO at normal state with an n-type material Ag-paste forms a quasi-pn junction which is responsible for the photovoltaic behavior of YBCO ceramics at high temperatures.Our findings may pave the way to new applications of photon-electronic devices and shed further light on the proximity effect at the superconductor-metal interface.

View Article: PubMed Central - PubMed

Affiliation: 1] College of Physics and Electronic Engineering, Henan Normal University, Xinxiang 453007, P. R. China [2] Henan Key Laboratory of Photovoltaic Materials, Xinxiang 453007, P. R. China.

ABSTRACT
We report remarkable photovoltaic effect in YBa2Cu3O6.96 (YBCO) ceramic between 50 and 300 K induced by blue-laser illumination, which is directly related to the superconductivity of YBCO and the YBCO-metallic electrode interface. There is a polarity reversal for the open circuit voltage Voc and short circuit current Isc when YBCO undergoes a transition from superconducting to resistive state. We show that there exists an electrical potential across the superconductor-normal metal interface, which provides the separation force for the photo-induced electron-hole pairs. This interface potential directs from YBCO to the metal electrode when YBCO is superconducting and switches to the opposite direction when YBCO becomes nonsuperconducting. The origin of the potential may be readily associated with the proximity effect at metal-superconductor interface when YBCO is superconducting and its value is estimated to be ~10(-8) mV at 50 K with a laser intensity of 502 mW/cm(2). Combination of a p-type material YBCO at normal state with an n-type material Ag-paste forms a quasi-pn junction which is responsible for the photovoltaic behavior of YBCO ceramics at high temperatures. Our findings may pave the way to new applications of photon-electronic devices and shed further light on the proximity effect at the superconductor-metal interface.

No MeSH data available.


Related in: MedlinePlus

Temperature dependence of photovoltaic characteristics for YBCO-Ag paste system under 502 mW/cm2 laser illumination.The laser spot center is positioned around the cathode electrodes (see Fig. 1i). a, I-V curves obtained from 50 to 90 K (top) and from 100 to 300 K (bottom) with a temperature increment of 5 K and 20 K, respectively. Inset a shows I-V characteristics at several temperatures in dark. All the curves cross the origin point. b, open circuit voltage Voc and short circuit current Isc (top) and the differential resistance, dV/dI, of YBCO (bottom) as a function of temperature. The zero resistance superconducting transition temperature Tcp is not given because it is too close to Tc0.
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f3: Temperature dependence of photovoltaic characteristics for YBCO-Ag paste system under 502 mW/cm2 laser illumination.The laser spot center is positioned around the cathode electrodes (see Fig. 1i). a, I-V curves obtained from 50 to 90 K (top) and from 100 to 300 K (bottom) with a temperature increment of 5 K and 20 K, respectively. Inset a shows I-V characteristics at several temperatures in dark. All the curves cross the origin point. b, open circuit voltage Voc and short circuit current Isc (top) and the differential resistance, dV/dI, of YBCO (bottom) as a function of temperature. The zero resistance superconducting transition temperature Tcp is not given because it is too close to Tc0.

Mentions: To investigate the effect of temperature on the photovoltaic properties, the metal-superconductor system was irradiated at the cathode with blue laser of intensity 502 mW/cm2. I-V curves obtained at selected temperatures between 50 and 300 K are given in Fig. 3a. The open circuit voltage Voc, short circuit current Isc and the differential resistance can then be obtained from these I-V curves and are shown in Fig. 3b. Without light illumination, all the I-V curves measured at different temperatures pass the origin as expected (inset of Fig. 3a). The I-V characteristics change drastically with increasing temperature when the system is illuminated by a relatively strong laser beam (502 mW/cm2). At low temperatures the I-V curves are straight lines parallel to the I-axis with negative values of Voc. This curve moves upwards with increasing temperature, and gradually turns into a line with a nonzero slope at a critical temperature Tcp (Fig. 3a (top)). It seems that all the I-V characteristic curves rotate around a point in the third quadrant. Voc increases from a negative value to a positive one while Isc decreases from a positive to a negative value. Above the original superconducting transition temperature Tc of YBCO, the I-V curve changes rather differently with temperature (bottom of Fig. 3a). Firstly, the rotation center of the I-V curves moves to the first quadrant. Secondly, Voc keeps decreasing and Isc increasing with increasing temperature (top of Fig. 3b). Thirdly, the slope of the I-V curves increase linearly with temperature resulting in a positive temperature coefficient of resistance for YBCO (bottom of Fig. 3b).


Origin of photovoltaic effect in superconducting YBa2Cu3O6.96 ceramics.

Yang F, Han MY, Chang FG - Sci Rep (2015)

Temperature dependence of photovoltaic characteristics for YBCO-Ag paste system under 502 mW/cm2 laser illumination.The laser spot center is positioned around the cathode electrodes (see Fig. 1i). a, I-V curves obtained from 50 to 90 K (top) and from 100 to 300 K (bottom) with a temperature increment of 5 K and 20 K, respectively. Inset a shows I-V characteristics at several temperatures in dark. All the curves cross the origin point. b, open circuit voltage Voc and short circuit current Isc (top) and the differential resistance, dV/dI, of YBCO (bottom) as a function of temperature. The zero resistance superconducting transition temperature Tcp is not given because it is too close to Tc0.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4477232&req=5

f3: Temperature dependence of photovoltaic characteristics for YBCO-Ag paste system under 502 mW/cm2 laser illumination.The laser spot center is positioned around the cathode electrodes (see Fig. 1i). a, I-V curves obtained from 50 to 90 K (top) and from 100 to 300 K (bottom) with a temperature increment of 5 K and 20 K, respectively. Inset a shows I-V characteristics at several temperatures in dark. All the curves cross the origin point. b, open circuit voltage Voc and short circuit current Isc (top) and the differential resistance, dV/dI, of YBCO (bottom) as a function of temperature. The zero resistance superconducting transition temperature Tcp is not given because it is too close to Tc0.
Mentions: To investigate the effect of temperature on the photovoltaic properties, the metal-superconductor system was irradiated at the cathode with blue laser of intensity 502 mW/cm2. I-V curves obtained at selected temperatures between 50 and 300 K are given in Fig. 3a. The open circuit voltage Voc, short circuit current Isc and the differential resistance can then be obtained from these I-V curves and are shown in Fig. 3b. Without light illumination, all the I-V curves measured at different temperatures pass the origin as expected (inset of Fig. 3a). The I-V characteristics change drastically with increasing temperature when the system is illuminated by a relatively strong laser beam (502 mW/cm2). At low temperatures the I-V curves are straight lines parallel to the I-axis with negative values of Voc. This curve moves upwards with increasing temperature, and gradually turns into a line with a nonzero slope at a critical temperature Tcp (Fig. 3a (top)). It seems that all the I-V characteristic curves rotate around a point in the third quadrant. Voc increases from a negative value to a positive one while Isc decreases from a positive to a negative value. Above the original superconducting transition temperature Tc of YBCO, the I-V curve changes rather differently with temperature (bottom of Fig. 3a). Firstly, the rotation center of the I-V curves moves to the first quadrant. Secondly, Voc keeps decreasing and Isc increasing with increasing temperature (top of Fig. 3b). Thirdly, the slope of the I-V curves increase linearly with temperature resulting in a positive temperature coefficient of resistance for YBCO (bottom of Fig. 3b).

Bottom Line: The origin of the potential may be readily associated with the proximity effect at metal-superconductor interface when YBCO is superconducting and its value is estimated to be ~10(-8) mV at 50 K with a laser intensity of 502 mW/cm(2).Combination of a p-type material YBCO at normal state with an n-type material Ag-paste forms a quasi-pn junction which is responsible for the photovoltaic behavior of YBCO ceramics at high temperatures.Our findings may pave the way to new applications of photon-electronic devices and shed further light on the proximity effect at the superconductor-metal interface.

View Article: PubMed Central - PubMed

Affiliation: 1] College of Physics and Electronic Engineering, Henan Normal University, Xinxiang 453007, P. R. China [2] Henan Key Laboratory of Photovoltaic Materials, Xinxiang 453007, P. R. China.

ABSTRACT
We report remarkable photovoltaic effect in YBa2Cu3O6.96 (YBCO) ceramic between 50 and 300 K induced by blue-laser illumination, which is directly related to the superconductivity of YBCO and the YBCO-metallic electrode interface. There is a polarity reversal for the open circuit voltage Voc and short circuit current Isc when YBCO undergoes a transition from superconducting to resistive state. We show that there exists an electrical potential across the superconductor-normal metal interface, which provides the separation force for the photo-induced electron-hole pairs. This interface potential directs from YBCO to the metal electrode when YBCO is superconducting and switches to the opposite direction when YBCO becomes nonsuperconducting. The origin of the potential may be readily associated with the proximity effect at metal-superconductor interface when YBCO is superconducting and its value is estimated to be ~10(-8) mV at 50 K with a laser intensity of 502 mW/cm(2). Combination of a p-type material YBCO at normal state with an n-type material Ag-paste forms a quasi-pn junction which is responsible for the photovoltaic behavior of YBCO ceramics at high temperatures. Our findings may pave the way to new applications of photon-electronic devices and shed further light on the proximity effect at the superconductor-metal interface.

No MeSH data available.


Related in: MedlinePlus