In an ideal world, all photons reaching a PV device are transmitted only to the active region where the conversion process occurs.
Due to the refractive index of the materials used, light shall be reflected from the front surface of the device (to mitigate which anti-reflection coatings are applied). In the case of thin- film devices one should also consider that light may be transmitted through the sample.
The total reflectance (diffuse and specular), and the total transmittance (diffuse and normal), of the device can be measured with the aid of an integrating sphere.
In addition to providing a manner of determining device IQE (below), these measurements also permit the characterisation of anti–reflection coatings and the transmission of thin film layers.
Categories: Solar & Photovoltaics