the structure and material of SPC.n is the ideality factor,which is between I to 2.q is the electron's charge.kB is the Boltzmann constant.T is the temperature of the junction.Under certain illumination,if the SPC is short,then V=0.We can get the short circuit current. Isc =Iph (2) Figure 2 presents SPC's short circuit current as a function of illumination. (2)open circuit voltage and illumination of SPC If the SPC is open circuit,then I=0.From Equation 1 and 2,we get the open circuit voltage nk T (3) q Figure 2 presents SPC's open circuit voltage as a function of illumination. Uoe/Vt 开路电压 牛Isc/uA 0.5 20 0.4 16 0.3 短路电流 白 0.2 8 0.1 4 0 200040006000800010000 E/Lux (a)Inverse-bias condition (b)Non-biased condition Figure 2 Properties of silicon photocell as a function of Figure 3 Two basic work conditions for silicon Illumination photocell 3)The I-V character of SPC Different from the normal diode,the SPC usually work under the inverse-biased condition(Fig 3a)or non-biased condition(Fig 3b).When the SPC is connected with a load RL,its I-V curve is shown in Fig.4.Even under the inverse bias or non-bias condition,there is a backward current, which is the main difference between SPC and the normal diode.Without illumination,there is a very small backward leading current that is called dark current. (1)Inverse-bias(Third quadrant in the Fig.4) Under the inverse bias condition,for a wide range of applied voltage and load resistance,the photoelectric current linearly depends on the power of incident light.Since the photoelectric current is nearly independent to the bias voltage and load resistance within a very large dynamic -3-- 3 - the structure and material of SPC. n is the ideality factor, which is between 1 to 2. q is the electron’s charge. kB is the Boltzmann constant. T is the temperature of the junction. Under certain illumination, if the SPC is short, then V=0. We can get the short circuit current. SC Ph I = I （2） Figure 2 presents SPC’s short circuit current as a function of illumination. (2) open circuit voltage and illumination of SPC If the SPC is open circuit, then I=0. From Equation 1 and 2, we get the open circuit voltage ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ = ln +1 0 I I q nk T V B SC OC （3） Figure 2 presents SPC’s open circuit voltage as a function of illumination. 3) The I-V character of SPC Different from the normal diode, the SPC usually work under the inverse-biased condition (Fig 3a) or non-biased condition (Fig 3b). When the SPC is connected with a load RL, its I-V curve is shown in Fig.4. Even under the inverse bias or non-bias condition, there is a backward current, which is the main difference between SPC and the normal diode. Without illumination, there is a very small backward leading current that is called dark current. (1) Inverse-bias (Third quadrant in the Fig. 4) Under the inverse bias condition, for a wide range of applied voltage and load resistance, the photoelectric current linearly depends on the power of incident light. Since the photoelectric current is nearly independent to the bias voltage and load resistance within a very large dynamic Figure 2 Properties of silicon photocell as a function of Illumination （a）Inverse-bias condition（b）Non-biased condition Figure 3 Two basic work conditions for silicon photocell