Estudo dos parâmetros fotovoltaicos de molibdato de cálcio

Abstract

The constant search for new technologies to supply the ever increasing world's energy demand, caused by population growth and industrial development, makes the need for more e cient energy conversion devices. One prominent device, already established as a large research topic, is the photovoltaic cell, that converts solar energy into electric. Nowadays, perovskite type materials have been widely used for this speci c application, however, the scheelite class of materials, ABO still needs to be improved for utilization as photovoltaic cells, which arise the necessity for novel studies. The Calcium Molybdate (CMO) belongs to this class of ceramic materials and has electrical and optical properties extremely promising for the application as a third generation solar cell photoelectrode; reason why this material has been chosen for the development of this work. Thus, the CMO was obtained by the Microwave-Assisted Hydrothermal method (HAM), method chosen for its advantages over other more traditional techniques for sample preparation, such as a smaller synthesys time and a larger nucleation rate. Structural, optical and morphological characterizations were implemented before the materials' application as photoelectrode, in order to verify if the samples showed the necessary conditions for the required application. Moreover, in this work we synthesized six (06) CMO samples, with di erent parameters such as temperature and synthesis pH at 100➦C (pHs 4, 7 e 10) and 140➦C (pHs 4, 7 e 10), respectively, to correlate the pH in uence to the photovoltaic parameters, obtained through the application of the material as a third generation solar cell photoelectrode. It was found that the sample synthesized with pH 4 at 100➦C applied as photoelectrode showed the best value for maximum current density (J 4 ), equals to 0.145 mA=cm 2 , the biggest one compared to all the other devices. Nevertheless, this sample presents an anomalous behavior divergent from the typical photovoltaic behavior, thus making it impossible to calculate the cell ll factor (FF) and e ciency ( ). Between all samples, the one with pH 10 at 100➦C presented the best e ciency, 0.49, value close to the best results found in literature. The samples synthesized at 140➦C showed worse results, compared to those synthesized at 100➦C. For a better analysis of the electric responses addressed in this work, the cells assembly was repeated with an optimization of the CMO lms; the same anomalous behavior for the samples with pH 4 was reproduced. Also, the samples with pH 10 at 100➦C once again showed the best e ciency compared to all the other samples.