Partial substitution of the CdS buffer layer with interplay of fullerenes in kesterite solar cells†
Over the last few decades, significant progress has been made with inorganic materials to enable them as next generation photovoltaic materials that can fulfil the demands of green energy. 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 semiconductors. We report the usage of n-type fullerene 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 reveal that using C60 as an interlayer increases the built-in potential, suggesting reduction in the interfacial recombination. This promotes charge conduction, resulting in an increased open circuit voltage and thus device performance.