Screen-printed dopant paste interdigitated back contact solar cells

We report on progress made with an all-screen-printed interdigitated back contact (IBC) solar cell process. The rear side interdigitated doping pattern is defined using screen printed boron and phosphorus dopant pastes with thermal drive-in. High printing and doping fidelity as well as high wafer bulk lifetime are demonstrated. Screen printed fire-through metal pastes are also used for contacts. We present pilot line data for n-type CZ silicon, 156 mm pseudo-square cells achieving a 21.3% champion efficiency and 21% median efficiency. Improvements to the boron emitter metal contact are highlighted as a path to achieve 22% efficiency.