Combinations of evaporation and screen printing techniques for fabricating ITO-TIN (Sn)-p-type silicon solar cells

Abstract

Combinations of evaporation and thick-film screen printing techniques were used for fabricating indium tin oxide (ITO)-tin (Sn)-p-type silicon heterostructure solar cells. A 100 nm tin layer was evaporated onto the front surface of p-type silicon substrates and screen printed ITO was deposited on top of the tin layer. These substrates were then fired for 30 minutes at various firing temperatures ranging from 450°C to 650°C inclusive, increased in steps of 50°C. The ITO film, in this structure, acts as a conducting window layer. Optical measurements show that they are highly transparent in the visible band region, and the electrical properties show that they are reasonably conductive. The sheet resistance of the ITO films is about 290 Ω/□, measured during annealing in vacuum conditions at a temperature of 300°C and gradually increases after ageing for a few days in atmosphere conditions. Typical values obtained for these cells are an open circuit voltage, Voc = 0.360 V, a short circuit current density, Jsc = 16.4 mA/cm2 with a fill factor, FF = 0.34 and efficiency of about ν = 2.5% under 80 mW/cm2 simulated illumination. This illumination is equivalent to air mass 2 (AM2), i.e. radiation at the surface of the earth with an illumination of 800-850 W/m2. © 1989.