Laser-Doped Back-Contact Solar Cells

We present laser-doped interdigitated back-contacted solar cells with a record efficiency η = 22.0%. The high versatility and spatial resolution of our laser doping process enable local n-type and p-type doping with a precision below 30 μm and avoid any masking for doping. Nevertheless, the presented solar cells use photolithography (masking) to define the contact area and metallization layout. Quasi-steady-state photoconductance measurements prove the low-saturation current density of the laser doping. We process solar cells with varied pitch and emitter fraction and compare their measured current density-voltage characteristics with a 3-D solar cell simulation. The good agreement of the simulation and experimental data allows a reliable efficiency forecast when optimizations are applied. Furthermore, the influence of the base-busbar region on solar cell performance is discussed.