Laser ablation - a new low-cost approach for passivated rear contact formation in crystalline silicon solar cell technology

The ablation of passivating layers using laser radiation offers a new way of defining the rear contact pattern for the passivated emitter and rear cell (PERC) concept. The KrF-Excimer laser has been identified to be a suitable tool for the ablation process. The laser process has been optimised in order to realise well-defined and shallow holes in silicon dioxide and silicon nitride using excimer laser ablation. Solar cell efficiencies of up to 20.4 % and 19.7 %, respectively have been realised by applying this process to the W-PERC cell concept without using any laserdainage etching. Process times below 3 s can be realised for enhanced use of beam power using a microlens array. The process can be fully integrated in a vacuum process for rear contact formation. The laser ablation approach seems to offer a bright perspective of highly efficient rear contact formation for future thin and large solar cells.