Photolithography-free interdigitated back-contacted silicon heterojunction solar cells with efficiency >21%

We report on the development of interdigitated back-contacted silicon heterojunction solar cells with conversion efficiencies well above 21%. Doped hydrogenated amorphous silicon layers, needed for electron and hole collection, are patterned via in-situ shadow masking whereas transparent conductive oxide and metal layers, of the back electrodes, are defined via hot melt inkjet printing of an etch resist and subsequent wet etching. Our technology is therefore photolithography-free and avoids any high-temperature step. The best fabricated solar cell presents a high short-circuit current density of 39.9 mA/cm
²
, an open-circuit voltage of 724 mV and a fill factor of 74.5% resulting in a conversion efficiency of 21.5%, with a strong upside potential. We report also on a silver-free IBC-SHJ solar cell with conversion efficiency >20%.