A Study On The Reliability Characterization Methods Of Compound Thin-film Solar Cells

With the development of human society,the demand for energy is increasing.However,the traditional fossil energy reserves are limited and its extensive use will lead to serious environmental problems.Therefore,looking for clean and renewable energy has become the focus of all countries.Among all kinds of new clean energy,solar energy has the advantage of wide distribution,no pollution and sustainability.So it is considered as one of the most promising energy sources.Currently,the use of solar energy mainly in three forms:photo-thermal utilization,photo-chemical utilization,photovoltaic utilization.The utilization of solar convert solar radiation directly into electricity by using solar photovoltaic effect,the core part of it is the solar cell.The Compound thin film solar cell is one of the solar cells which has a good development prospect.Compared with the silicon material,the compound semiconductor materials almost have direct-band-gap,and its light absorption coefficient is high.Only a micron thickness,we can produce high-efficiency solar cells.The compound semiconductor materials also have a larger forbidden bandwidth and a higher irradiation resistance than the silicon material.With the popularization and application of the solar cells,its quality in production process and the reliability in utilization process has also attracted more and more attentions.Currently,there are many ways to characterize the reliability of solar cells,such as by measuring the I-V characteristics of solar cells,we can extract some electrical parameters;directly examining the defect of the solar cells via optical microscope and scanning electron microscope;researching reverse breakdown characteristics of the solar cells through the electroluminescent and so on.But these methods mostly lack of sensitivity,long testing cycle and destructive.Noise as a tool for the evaluation of the quality and reliability of electronic components,its sensitivity,non-destructive has been widely recognized.Via analyzing the defects in the material and the noise produced by these defects,we can obtain more information about the performance and reliability of the components.Therefore,it is vital for us to study the noise characterization method of thin film solar cell based on the study of electrical characterization method.Based on the above background,two typical compound thin film solar cells-Ga As,Cd Te thin film solar cells were selected,and their failure modes and failure mechanism were studied.Then,according to their respective failure modes and failure mechanism,we designed and carried out the corresponding accelerated stress experiment.For the Cd Te thin film solar cell,we carried out the high temperature degradation experiments,ESD experiments.For Ga As thin film solar cells,we carried out the ESD contrast experiment.By analyzing the changes of the electrical parameters and the noise parameters of the solar cells during the experiment,we characterized the variation law of the battery performance and reliability.At the same time,we analyzed the reasons for these changes.In the process of analysis,the reliability and sensitivity of the noise characterization methods are proved by comparing the relative change rate of the electrical parameters and the noise parameters.Finally,according to the failure mechanism of the two solar cells and the mechanism of the noise in the solar cells,the low-frequency noise characterization models of the two kinds of cells was established.