Surface Passivation of Crystalline Silicon Solar Cells by Cr:ZnO Coating Layers

This article explores the synthesis of ZnO thin films through a straightforward co-precipitation method, both with and without Cr doping, and their subsequent application via spin-coating onto silicon substrates. The investigation focuses on discerning the impact of Cr doping content on the structural and opto-electronic properties of the films. Techniques such as atomic force microscopy (AFM) and X-ray diffraction (XRD) were employed for the analysis of surface morphology and crystal structure. Additionally, methods involving Fourier-transform infrared spectroscopy (FTIR) and photoconductance were utilized to assess surface passivation and reflectivity in both Cr-doped and undoped ZnO films. Notably, the introduction of Chromium doping resulted in a significant enhancement of the effective minority carrier lifetime, elevating it from 1.5 to 88 μs at a minority carrier density (n) of 10¹⁴ cm^-3. Furthermore, the reflectivity at λ= 500 nm witnessed a reduction from 30% to approximately 7% when silicon was coated with Cr-doped ZnO.