(1)P()is the measured light intensity.Since the 100 short-circuit current is proportional to the illumination,we can use short-circuit to 80 characterize the intensity of the incident light. 60 (2)The light source in the experiment is the ultra 立 40 high intensity white color LED,the relation 20 between intensity and wavelength can be found in the manual. 0 400600800 10001200 (3)The optical filter used in the experiment can 元(nm) let some light pass.Filters are characterized by center wavelength,width (AN,and maximum Figure 5 Spectral curve of silicon photocell transmissivity (T).Those parameters are labeled on the instruments. The relative sensitivity is defined as K()=K(a) (6) Kn K is the maximum sensitivity for K ( 3. Solar Cell 1)structure of solar cell We use crystalline silicon solar cells as an example.It's basic structure is presented in Fig.6. Crystalline silicon solar cells consist of large-area PN junction.Usually,n/p homojunction structure is used.A heavily doped n-type thin layer(~0.3 um)is fabricated using diffusion method on the surface of p-type silicon(~10 cm x 10 cm large and about 500 um thick) using diffusion method.Metal grid is prepared on the n-type layer as the front contact electrode.The back of p-type silicon is fully covered with metallic film as the back contact electrode.In order to reduce the light reflection loss,anti-reflection coating is also used on the surface. -5-- 5 - (1) P(λ) is the measured light intensity. Since the short-circuit current is proportional to the illumination, we can use short-circuit to characterize the intensity of the incident light. (2) The light source in the experiment is the ultra high intensity white color LED, the relation between intensity and wavelength can be found in the manual. (3) The optical filter used in the experiment can let some light pass. Filters are characterized by center wavelength, width (∆λ), and maximum transmissivity (T). Those parameters are labeled on the instruments. The relative sensitivity is defined as ( ) ( ) m r K K K λ λ = （6） Km is the maximum sensitivity for K（λ） 3. Solar Cell 1) structure of solar cell We use crystalline silicon solar cells as an example. It’s basic structure is presented in Fig. 6. Crystalline silicon solar cells consist of large-area PN junction. Usually, n+ /p homojunction structure is used. A heavily doped n-type thin layer (~ 0.3 µm) is fabricated using diffusion method on the surface of p-type silicon (~ 10 cm × 10 cm large and about 500 µm thick) using diffusion method. Metal grid is prepared on the n-type layer as the front contact electrode. The back of p-type silicon is fully covered with metallic film as the back contact electrode. In order to reduce the light reflection loss, anti-reflection coating is also used on the surface. 20 40 60 80 100 0 400 600 800 1000 1200 Kr %( ) nm Figure 5 Spectral curve of silicon photocell