Electrically flat/optically rough substrates for efficiencies above 10% in n-i-p thin-film silicon solar cells

Abstract

Substrates with extremely low roughness to allow the growth of good-quality silicon material but that nevertheless present high light trapping properties are presented. In a first application, silver reflectors are used in single and tandem-junction amorphous silicon (a-Si:H) solar cells. High initial (stable) efficiencies of 10.4 % (8.1 %) for single-junction a-Si:H cells on glass and 11.1 % (9.2 %) for tandem-junction a-Si:H/a-Si:H cells on plastic are obtained. A second application better suited to multi-junction solar cells based on microcrystalline silicon (μc-Si:H) solar cells is presented: the substrate consists of rough zinc oxide (ZnO) grown on a flat silver reflector which is covered with a-Si:H; polishing of this structure yields an a-Si:H/ZnO interface that provides high light scattering even though the cell is deposited on a flat interface. We present results of ~ 4-μm-thick μc-Si:H solar cells prepared on such substrates with high open-circuit voltages of 520 mV. A large relative efficiency gain of 20% is observed compared to a co-deposited cell grown directly on an optimized textured substrate.

Inorganic photovoltaics – Planar and nanostructured devices

“…These defects can 541 produce fracture during the solar cells processing and lower the performance of the solar cells 542 [43]. Thus, one of the necessary steps to obtain high-efficiency Si solar cell is to introduce 543 saw damage etching of the wafer at the beginning of the fabrication process, and it is carried 544 out by immersion of the wafer in a chemical solution [27]. 545 Optical losses of the solar cells can be improved by means of a texturing process on 546 the front surface of the Si wafer [36].…”