Triple-junction amorphous/microcrystalline silicon solar cells: Towards industrially viable thin film solar technology

The status of the development of triple-junction (amorphous silicon/microcrystalline/microcrystalline silicon) test cells fabricated with up-scalable PECVD processes is given. A first draft of novel rather flat scattering superstrates with an optimized high bandgap amorphous silicon top cell including a carbon-free buffer at the p/i interface is presented. The careful optimization of the interfaces (including sub-oxide doped layers and buffers) and of the bulk crystallinity of the middle and bottom microcrystalline sub-cells allowed to reach a stabilized efficiency of 13.5 % (after 1000 h light-soaking, internal measurement). Sub-cells individual developments are discussed and their specific integration into the full triple-junction device with its optimization for AM1.5G illumination relying on a partly LED supported solar simulator characterization is presented.