Optical / Reflectance Photometry & Solar Cell Characterization

Reflectance study of materials give us information of the optical properties. General reflectivity is sensitive to complex dielectric function ε=ε₁+iε₂ where ε₁ is the real and ε₂ the imaginary part of this. In the wide frequency range the two parts related with Kramers-Kroning relations. Starting with the experimental data for the reflectivity R(ω) we can found the reflection coefficient r(ω) and the phase of reflectivity θ(ω) and we can calculate the refractive and absorption constant n(ω) and k(ω) and finally the frequency dependence of ε₁ and ε₂. With this procedure we can found the optical constants of each material. It’s a very useful tool for thick layers like a crystal.

Solar cells dark and photocurrent measurements show the series and shunt device resistance and finally the efficiency of the device. External quantum efficiency (EQE) measurements can be measure using spectrometer and power measurements for each wavelength.