Optimization\nof Selenization Condition for Efficiency\nCIGSe Solar Cells Based on Postselenization of CuInGa Precursors

The\ndegree of selenization of the CIGSe absorbers is controlled\nby regulating the parameters of the selenization reaction. The structure,\nelement distribution, phase composition of the CIGSe absorbers, and\nthe performances of the solar cells with different selenization degrees\nare studied. Insufficient selenization will lead to residual Cu<sub>2</sub>Se phase on the surface and insufficient Na diffusion, which\nwill affect the V<sub>Cu</sub><sup>+</sup> on the surface and the\nrecombination at the front interface. However, excessive selenization\nwill make the MoSe<sub>2</sub> layer thicken at the back interface\nof the CIGSe/Mo, resulting in the increase of the series resistance\nand the enhancement of the recombination at the back interface. The\nappropriate selenization degree is conducive to inhibiting the recombination\nat the front and back interfaces. Improved device performances can\nbe obtained by optimizing the selenization degree of the absorbers.