range,the SPC can be treated as a constant current source when the power of the incident light is certain. (2)non-bias (Fourth quadrant in the Fig.4) Under the non-bias state condition,the photoelectric current is proportional to the power of incident light only if the RL is small.As the RL increase,the relation between the photoelectric current and the power of incident light becomes nonlinear.The relation between the short-circuit current and the power of incident light without bias voltage is called the photoelectric character UN3.02.52.0-1.51.0-0.50 10020030p400 U/mV -5 R大 -10 -15 E2 -201 Es -25 R小 Ea 反向偏压工作区 1/uA 无偏压工作因 Figure 4 I-V curves of silicon photocells of SPC.The slope in the IL-P coordinator is defined as the SPC's responsiveness.R is a very important parameter to characterize the photoelectric conversion efficiency macroscopically. R=AIL (4) AP (A/w) Under non-bias condition,the SPC is not a constant current source when the load resistance varies a lot.It is just like a battery. Seen from the Fig.4,for each illumination,the intercept of load curve on the current axis is the short-circuit current Iph.The intercept on the voltage axis is the open voltage Voc 4)*Spectral response of SPC Figure 5 is the spectral characteristic curve of SPC.The vertical axis is the relative sensitivity Kr and the abscissa axis is the wavelength A From the Fig.5 we can see that the effective range of SPC is about from 450nm to 1100nm Sensitivity of SPC is defined as P(2) K=0T0)△M (5) -4-- 4 - range, the SPC can be treated as a constant current source when the power of the incident light is certain. (2) non-bias (Fourth quadrant in the Fig.4) Under the non-bias state condition, the photoelectric current is proportional to the power of incident light only if the RL is small. As the RL increase, the relation between the photoelectric current and the power of incident light becomes nonlinear. The relation between the short-circuit current and the power of incident light without bias voltage is called the photoelectric character of SPC. The slope in the IL-P coordinator is defined as the SPC's responsiveness. R is a very important parameter to characterize the photoelectric conversion efficiency macroscopically. ( ) A / w Δ Δ μ μ P I R L = （4） Under non-bias condition, the SPC is not a constant current source when the load resistance varies a lot. It is just like a battery. Seen from the Fig.4, for each illumination, the intercept of load curve on the current axis is the short-circuit current IPh. The intercept on the voltage axis is the open voltage VOC 4) * Spectral response of SPC Figure 5 is the spectral characteristic curve of SPC. The vertical axis is the relative sensitivity Kr and the abscissa axis is the wavelength λ. From the Fig. 5 we can see that the effective range of SPC is about from 450nm to 1100nm Sensitivity of SPC is defined as ( ) ( ) η() () λ λ λ λ λ Δ = T P K （5） -0.5 0 100 200 300 400 -5 -10 -15 -20 -25 RL 大 反向偏压工作区 无偏压工作区 E3 E2 E1 U / V -3.0 -2.5 -2.0 -1.5 -1.0 U / mV E4 I / A RL 小 Figure 4 I-V curves of silicon photocells