Thin film absorber selection to pair with silicon for 1-Sun tandem photovoltaics

•Upper limit efficiencies are calculated for tandem thin-film + silicon solar cells.•Output voltage scaled to the bandgap is used as a thin-film quality parameter.•Optical absorption is tied to the Tauc model for near-edge photon energies.•SQ optimization is performed for selected thin-film composition families.•Larger bandgap is required when lower quality thin films are used.