tailieunhanh - Solar Cells Thin Film Technologies Part 9

Tham khảo tài liệu 'solar cells thin film technologies part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Influence of Post-Deposition Thermal Treatment on the Opto-Electronic Properties of Materials for CdTe CdS Solar Cells 229 The diode ideality factor A has been calculated from those curves and its behavior as function of HCF2Cl was also reported in Fig. 16 b. Specific processes occurring at the junction determined the reverse current and diode factor. In our case it was observed a decrease of the reverse current when the HCF2Cl partial pressure was increased. This behavior reached a minimum in the most efficient device obtained for this series corresponding to 40mbar HCF2Cl partial pressure Jsc cm2 Voc 820mV ff see Fig. 17 . An increase of 10mbar more reactive gas in the annealing chamber yields to a degradation of the reverse current that was increased of various orders of magnitude showing the high reactivity of the treatment and the impact of an excess annealing on the device electrical performance. At the same time from the behavior of A a variation of transport mechanism depending on the treatment conditions could be suggested Fig. 16 b . For the untreated sample A indicated that recombination current dominated the junction transport mechanism or that high injection conditions were present. An increase of the HCF2Cl partial pressure gave rise to a situation in which diffusion and recombination currents take place together until the case of 40mbar HCF2Cl partial pressure was reached where the minimum value of A appointed to a predominant diffusion current. The cell treated with 50mbar of reactive gas partial pressure showed a sharp modification by increasing again the diode factor n up to . The increase of the diode reverse saturation current was responsible for a drastic reduction of ff Fig16 b despite the JSC and VOC did not change appreciably from the others HCF2Cl annealed devices. Fig. 16. a Comparison among the dark reverse I-V curves for untreated and 20 30 40 and 50 mbar of HCF2Cl partial pressure treated solar cells b Diode