Comprehensive study of solar cell structure defects by means of noise and light emission analysis

This paper discusses the issue of silicon solar cells localized defects from metrological and physical points of view. Structure imperfections represent the real problem because of solar cells long-term degradation and conversion efficiency decreasing. To this aim we pay our attention to research relating to the defect light emission and correlation with rectangular microplasma fluctuation. A sensitive CCD camera has been used for mapping of surface photon emission. The operation point of the samples has been set to reverse bias mode, and different electric field intensity was applied. We managed to get interesting information using a combination of optical investigation and electrical noise measurement in time and spectral domain. It will be revealed that a direct correlation between noise and photon emission exists and the results related to several defect spots are presented in detail in this paper

Microscale comparison of solar cell recombination centers

The aim of this work is an experimental microscale comparison of several imperfection types of silicon solar cells which emit visible light under reverse bias condition. The setup with scanning probe microscope (SPM) and sensitive detector is used for the measurement of light emission in microscale. Used SPM allows a measurement of Light Beam Induced Current (LBIC) with high spatial resolution together with sample topography. Due to a number of observed defects that have no correlation with surface topography, we have found out that there are also defects having strong correlation with surface topography. In the most cases, investigated inhomogeneites could not be localized via light induced beam technique

Electromagnetic and acoustic emission signals continual measurement and real time processing

Stochastic electromagnetic and acoustic emission signals may be observed when the solid dielectric materials are mechanically stressed. Study of these signals may be used for indication of micro-crack formation in stressed materials. This paper describes the methodology, which was developed specially for electromagnetic and acoustic emission signals continual measurement and real time processing

Impact of local defects on photon emission, electric current fluctuation and reliability of silicon solar cells studied by electro-optical methods

This paper, for the first time, investigates localized defects of silicon solar cells. These imperfections represent real problem because of solar cell long-term degradation and decreasing conversion efficiency. To solve this issue, this paper does systematic research about optical investigation of local defect spots and correlation with rectangular microplasma fluctuation. Sensitive CCD camera has been used for mapping of surface photon emission. The operation point of the samples has been set to reverse bias mode and the different electric field intensity was applied. It turns out, that some solar cells exhibit an imperfection in the bulk and close to the edges. Nevertheless, we confine ourselves to bulk defects of potential barrier. We managed to get interesting information using combination of optical investigations and electrical noise measurement in the time and spectral domain. It will be revealed that a direct correlation between noise and photon emission exists and the results related to several defect spots are presented in detail in this paper

Statistical characteristics of electromagnetic emission signals of mechanical loaded composite samples

This article presents study of statistical characteristics of EME signals. The theoretical part contains a description of stochastic nature of electromagnetic emission. We describe the measuring system, the sequence of the experiment, statistical characteristics (probability density function, mean quantity and dispersion) and spectral analysis (voltage and current power spectral density of measured EME signals). In the practical part of the article we also have compared results obtained on the basis of experiment with theory