Tham khảo tài liệu 'solar cells silicon wafer based technologies part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Characterization of Thin Films for Solar Cells and Photodetectors and Possibilities for Improvement of Solar Cells Characteristics 291 contribute to the diode current. Since the ideality factor is the direct indicator of the output parameter dependence on the electrical transport properties measurements of the n V dependence along with the I-V measurements at different irradiation doses could narrow down possibilities of the dominant current component. Also values of the ideality factor could indicate not only the transport mechanism but indirectly the presence and possible activation of the defects and impurities acting as recombination and or tunneling centers. The influence of the ideality factor on the solar cell efficiency is predominantly through the voltage . the decrease of the efficiency with the increase of the ideality factor is the result of the voltage decrease in the maximum power point. Physical basis of such dependence lies in the connection between the ideality factor and saturation current density shown in Fig. 9 for different types of solar cells . 1E-6- 7l 10l 1E-7- 5l Ẹ 5 1E-8-5 . i 4p 1E-9 . 1p 1c 1E-10 -I-1--- -1-- --1--- --1- ---1-- --1--- --1-- ---1- 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 n Fig. 9. Saturation current dencity dependence on ideality factor Vasic et al. 2000 . Direct connection between Jo and n nearly exponential increase of saturation current density with the increase of n produces the decrease of the efficiency with the increase of either of these parameters. In the radiation environment such an increase is usually the result of induced defects and or activation of the existent impurities that could act as a recombination centers for the charge carriers altering the dominant current transport. Determination of the dominant current mechanism is very difficult because the relative magnitude of these components depend on various parameters such as density of the interface states concentration of the impurity defects and also .
