Papers by Keyword: Photovoltaic Effect

Abstract: The photovoltaic effect in Ag/Bi_0.9La_0.1FeO₃/La_0.7Sr_0.3MnO₃ heterostructures was investigated and the short circuit photocurrent was found to be strongly dependent on the polarization orientation and oxygen vacancies (V_Os) distribution. The photocurrent direction was switched accompanying polarization switching. Besides, according to manipulate the V_Os accumulated at either the Ag/Bi_0.9La_0.1FeO₃ or the Bi_0.9La_0.1FeO₃/La_0.7Sr_0.3MnO₃ interface by electric pulses, obvious enhancement of photovoltaic effects was obtained. These results can be explained well using the concepts of drift current and diffusion current controlled by the combination of oxygen vacancies and polarization. This work provides deep insights into the nature of photovoltaic effects in ferroelectric films, and will facilitate the advanced design devices combining spintronic, electronic, and optical functionalities.

Abstract: Solar energy is an inexhaustible and renewable energy without environmental pollution. Solar energy can be used in three kinds of forms: solar thermal energy, photochemical conversion and photovoltaic power generation. Among these, the final form of photovoltaic power generation is electricity which can be transported, applied and stored conveniently. On the basis of photovoltaic effect, solar cell is developed as a new technology to convert light energy into electrical energy using semiconductor. Up to now the two key problems of the development of solar cells are how to improve the conversion efficiency and reduce cost. Therefore, the material and production technology used for solar cells are discussed based on improving conversion efficiency in this article.

Abstract: All photovoltaic panel heats up when exposed to sunlight and this heating reduces the electrical power output of the same. This work presents the use of this unwanted waste heat, converting it into thermal energy directly by means of the Seebeck effect, which is the direct conversion of thermal energy into electrical energy by means of an arrangement of semiconductor materials that when exposed to temperature gradients generate electric current. In this work emphasis was placed on the influence of temperature on generation processes involved. Thus, the theoretical evaluation, it presents the mathematical models of thermoelectric and photovoltaic systems by raising the curves of voltage, current and electric power generated, and analyses the influence of temperature in each model. To obtain the simulation curves it uses MATLAB ® 5.3, taking into account the parameters of thermoelectric modules and real photovoltaic cells. In practical evaluation, a prototype was assembled containing thermoelectric module attached to the bottom of a photovoltaic panel in order to use the heat energy absorbed by the panel. The data were stored and analyzed, where we observed the influence of temperature in both systems, validating the mathematical modeling. It is the applicability of the mathematical model given the results obtained with the prototype system.

Abstract: This paper studied the impact of silicon oxide layer on photovoltaic characteristic of iron-doped amorphous carbon film/silicon heterojunction (a-C:Fe/Si). The results show that a native SiO2 layer on the silicon surface can provide a significant improvement of the a-C:Fe/Si devices’ photovoltaic performances, especially for the short circuit current and fill factor. This improvement partly may be attributed to the electron recombination process is suppressed and the interface is modified by the SiO2 film based on the open circuit voltage decay measurement.

Abstract: This article simulates the ferroelectric properties of a model of BaTiO3 thin film sandwiched between metal electrodes at the state of short circuit. We discussed the change of the depolarization and the Photocurrent generated within the film under UV irradiation. Comparing the polarization before and after the irradiation, the influence of the photovoltaic effect on the ferroelectric properties of BaTiO3 Thin Film is gained.

Abstract: The primary aim of this communication is to introduce a novel approach of preparation of solar cell, viz. PS based solar cell, which is on the basis of the basic principle of the well established photovoltaic effect. We carefully investigate the current-voltage characteristics of the PS-based solar cell by virtue of performing the measurement of both current and voltage of PS-based solar cell under the condition of the sunlight irradiation and priori to sunlight irradiation in the purpose of observing clearly the photovoltaic effect possessed by the PS based solar cell. Judging by the results obtained in this paper, we can safely draw the conclusion that porous silicon is a good candidate material for the preparation of solar cell, that is to say that our study is giving high hope for the industrial production of high efficient PS-based thin film solar cells.

Abstract: Photovoltaic lead lanthanum zirconate titanate films in a layered structure of different crystallographic orientations are fabricated by an optimized metalorganic deposition method. Such films of (001) orientation exhibit a photovoltaic electrical power of approximately 20 times higher than that of random films. The anisotropic optical properties of the oriented films, including dark conductivity, photoconductivity and photovoltaic tensor surfaces, are obtained quantitatively. These results show that the photovoltaic output current and power of the oriented films are highly improved to be equal to those of semiconductors and suitable for application in the optical sensor of micro-electro-mechanical systems.

Abstract: This paper reports on the formation of film structures and the highly improved photovoltaic output current of the lead lanthanum zirconate titanate (PLZT) employed. The photovoltaic effect of ferroelectrics has the advantage of its simple mechanisms of non-bias applications which are indispensable for semiconductor p-n junctions. But the output current of PLZT bulk is too low for use as a device current source. The PLZT film structure exhibited μA output current upon light illumination. The photovoltaic current of the PLZT film was more than 102 times than that of bulk PLZT. These differences are due to the characteristics of the design of the film including the configuration of the electrode. The PLZT film also has the advantage of easy output control and suitability for use on Si. Results show that the photovoltaic effect of the ferroelectric film is useful as the current source for micro-electro-mechanical systems (MEMS).