Recent progress in micromorph solar cells

• Published in: Journal of non-crystalline solids Vol. 227; pp. 1250 - 1256
• Main Authors: Meier, J, Dubail, S, Cuperus, J, Kroll, U, Platz, R, Torres, P, Anna Selvan, J.A, Pernet, P, Beck, N, Pellaton Vaucher, N, Hof, Ch, Fischer, D, Keppner, H, Shah, A
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.1998
• Subjects: Hydrogenated microcrystalline silicon; Micromorph; Solar cells; Thin film crystalline silicon; Very high frequency glow-discharge; Very high frequency glow-discharge; Solar cells; M220; Hydrogenated microcrystalline silicon; Thin film crystalline silicon; Micromorph; S270
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/S0022-3093(98)00352-4

Recently, we have demonstrated that intrinsic hydrogenated microcrystalline silicon, as deposited by the very high frequency glow-discharge technique, can be used as the active layers of p–i–n solar cells. Our microcrystalline silicon represents a new form of thin film crystalline silicon that can be deposited (in contrast to any other approach found in literature) at substrate temperatures as low as 200°C. The combination of amorphous and microcrystalline material leads to a `real' silicon-based tandem structure, which we label `micromorph' cell. Meanwhile, stabilised efficiencies of 10.7% have been confirmed. In this paper, we present an improved micromorph tandem cell with 12% stabilised efficiency measured under outdoor conditions. Dark conductivity and combined SIMS measurements performed on intrinsic microcrystalline silicon layers reveal a post-oxidation of the film surface. However, a perfect chemical stability of entire microcrystalline cells as well as micromorph cells is presented. Variations of the p/i interface treatment show that an increase of the open circuit voltages from 450 mV up to 568 mV are achievable for microcrystalline cells, but such devices have reduced fill factors.