Effectively transparent contacts (ETCs) for solar cells

Abstract

We have developed effectively transparent contacts (ETCs) that allow for increased current in heterojunction solar cells. Micro-meter scaled triangular cross-section grid fingers with micro-meter scaled distance redirect light efficiently to the active area of the solar cell and hence, omit losses through reflection at the front finger grid. Furthermore, the grid fingers are placed close together such that only a very thin layer of transparent conductive oxides (TCO) is necessary which avoids parasitic absorption and can decrease material costs. In this paper we experimentally show current enhancement of ~2 mA/cm^2 in silicon heterojunction solar cells using ETCs. 1 mA/cm^2 is gained through less parasitic absorption and 1 mA/cm^2 is gained by efficient redirection of light and therefore, absent shadowing losses.