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