Partial substitution of CdS buffer layer with interplay of fullerenes in kesterite solar cells

Over the last decades, significant progress has been made in inorganic materials to enable them as next generation photovoltaic materials that can fulfil the green energy demands. Cu₂ZnSn(S,Se)₄ stands out as a p-type absorber material due to exemption from scarce and strategic elements and its similarities with Cu₂InGa(S,Se)₄. Organic materials such as fullerenes and its derivatives are effective n-type semicondcutors. We report the usage of n-type fullerenes materials with kesterite-based absorbers in a thin film polycrystalline solar cell for the partial substitution of the CdS buffer layer with C₆₀ or C₇₀ fullerenes. Impedance measurements reveals that using C₆₀ as an interlayer increases built-in potential, suggesting reduction in the interfacial recombination. This promotes charge conduction, resulting in an increased open circuit voltage and thus device performance.