Measuring sheet resistance of CIGS solar cell's window layer by spatially resolved electroluminescence imaging

摘要

A spatially resolved electroluminescence (EL) imaging experiment is developedto measure the local sheet resistance of the window layer, directly on thecompleted CIGS cell. Our method can be applied to the EL imaging studies thatare made in fundamental studies as well as in in-line process inspection (1-3).The EL experiment consists in using solar cell as a light emitting device : avoltage is applied to the cell and its luminescence is detected. We develop ananalytical and quantitative model to simulate the behavior of CIGS solar cellsbased on the spread sheet resistance effect in the window layer. We determinethe repartition of the electric potential on the ZnO, for given cell'scharacteristics such as sheet resistance and contact geometries. Knowing therepartition of the potential, the EL intensity is estimated and theexperimental EL signal is fitted, which allows the determination of the windowlayer sheet resistance.