Entwicklung und Charakterisierung neuartiger Hochleistungssiliziumsolarzellen

Abstract

High efficiency silicon solar cells generally require sophisticated and complex processing sequences. The key features of such solar cells are: a silicon dioxide for surface passivation, front side texture, local rear contacts, a low front contact coverage ratio and a large minority carrier lifetime. Within this work novel high efficiency silicon solar cell concepts were developed and characterised. These allow an efficiency improvement and/or a simplification of the solar cell processing compared to conventional methods. These high efficiency silicon solar cell concepts are based on single or double sided mechanical surface texturing.Lifetime measurements and the efficiencies of front side textured solar cells of up to 20.1% demonstrate that the mechanical texturing is suitable for high efficiency solar cells. The silicon solar cell processes developed within this work are mainly investigated with regard to the contacting schemes particularly designed for mechanically textured surfaces. The thorough characterisation of solar cells with either front or rear side texture as well as double side texture with parallel or perpendicularly aligned V-grooves was done using IV-, spectral response and reflection measurements, fit procedures and multidimensional optical and electrical simulations. The following maximum efficiencies for the different cell concepts were achieved: EASY&SIMPLE (Especially Advanced Structuring with high Yield & Selective emitter IMPLEmentation) solar cell 18.1%; BOSS (BOth Sides Structured with vertically aligned V-grooves) solar cell 19.3%; MECOR (MEchanically CORrugated) solar cell 18.5%.