5% Efficient evaporated solidphase crystallised poly crystalline silicon thin-film solar cells

Abstract

The first energy conversion efficiencies of over 5% are reported for evaporated solid-phase crystallised (SPC) polycrystalline silicon thin-film solar cells. All cells have a size of 2 cm2 and are formed on planar glass superstrates. Back surface reflectance is provided by a simple coating with commercial white paint. The best cells have short-circuit current densities of about 19 mA/cm2 and external quantum efficiencies peaking at above 80%. The diffusion length in the base of the solar cells is larger than the base thickness, providing significant room for further efficiency improvements via an increased thickness of the base layer. Additional improvements are expected via the use of textured glass sheets, boosting the light trapping capabilities of the cells. Copyright © 2009 John Wiley & Sons, Ltd.