Optical modeling and optimizations of Cu2ZnSnSe4 solar cells using the modified transfer matrix method.

The fast and computationally inexpensive Modified Transfer Matrix Method (MTM) is employed to simulate the optical response of kesterite Cu2ZnSnSe4 solar cells. This method can partially take into account the scattering effects due to roughness at the interfaces between the layers of the stack. We analyzed the optical behavior of the whole cell structure by varying the thickness of the TCO layer (iZnO + ITO) between 50 and 1200 nm and the buffer CdS layer between 0 and 100 nm. We propose optimal combinations of the TCO/CdS thicknesses that can locally maximize the device photocurrent. We provide experimental data that qualitatively confirm our theoretical predictions.