Advanced materials processing for high-efficiency thin-film silicon solar cells

• Published in: Solar energy materials and solar cells 2013-12, Vol.119, p.156-162
• Main Authors: Matsui, Takuya, Kondo, Michio
• Format: Article
• Language: English
• Subjects: Chemical vapor deposition; Deposition; Devices; Electrodes; Grain boundaries; Hydrogenated amorphous silicon; Hydrogenated microcrystalline silicon; Light-soaking stability; Microstructure; Photovoltaic cells; Plasma-enhanced chemical vapor deposition; Silicon; Solar cells; Tandem cell; Thin films
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2013.05.056

We report on recent developments of hydrogenated amorphous silicon (a-Si:H) and microcrystalline silicon (μc-Si:H) for high-efficiency thin-film silicon solar cells. For a-Si:H, the light absorber layers were grown by a remote plasma technique using a triode electrode configuration in plasma-enhanced chemical vapor deposition (PECVD). Despite the relatively low deposition rate (0.01–0.03nm/s) compared to the conventional diode-type PECVD process (~0.2nm/s), the light-induced degradation in conversion efficiency (Δη/ηini) of single-junction solar cell is substantially reduced (e.g., Δη/ηini~10% at an absorber thickness of 250nm). As a result, we have obtained confirmed stabilized efficiencies of 9.6% and 11.9% for a-Si:H single-junction and a-Si:H/μc-Si:H tandem solar cells, respectively. Meanwhile, for μc-Si:H solar cells, we have investigated the structural properties of the μc-Si:H absorber layers grown at high deposition rates (>2nm/s). Several design criteria for the device grade μc-Si:H are proposed in terms of crystallographic orientation, grain size and grain boundary passivation. •a-Si:H layers are grown by PECVD with a triode electrode configuration.•The light-induced degradation of a-Si:H single-junction solar cell is substantially reduced.•Confirmed stabilized efficiencies of 9.6% (single junction) and 11.9% (tandem) are attained.•Structural properties of the μc-Si:H grown at high deposition rates (>2nm/s) are investigated.•Several design criteria for the device grade μc-Si:H are proposed.