Dispensing of Low-Temperature Silver Pastes

This paper shows the application of three low-temperature silver pastes on silicon heterojunction (SHJ) solar cells and Cu(In1-xGax)Se-2 modules by parallel dispensing and flatbed screen printing. The goal was to improve the finger shape as well as to increase the applicable process velocity resulting in reduced silver consumption per SHJ solar cell. In case of the thin-film technology an advantageous electrical performance of applying a front contact metallization on the modules was demonstrated. By dispensing optimized paste formulations, the core finger width was reduced to w(core) = 25 mu m and the optical aspect ratio was increased to AR(o) = 0.55 obtaining an efficiency gain of Delta eta = 0.3%abs. compared to the screen-printed reference on SHJ solar cells. Additionally, a simple integration solution for the parallel dispensing into existing industrial solar cell metallization process line was presented.