Ag-doped CuGaSe_2 as a precursor for thin film solar cells

摘要

For the preparation of p-CuGaAe_2 thin film absorbers, powder of single-phase CuGaSe_2 with deifned optical and electrical properites is requried as precursor material for soar cells. The motivation fo this work was that thin films shal be produced by a chemical vapour transport method using iodine as transport agent. Here we reprot on an optimised synthesis mehtod of this precursor material and discuss the effect of Ag-doping using Ag, AgSe_2 shwo a dominating emission at E=1.67 eV which is attributed to a free-to-bound transition where the acceptor bound state is assigned to copper vacancies. Ag-transiton with copper vacancies as acceptros and selenium vacancieks as donors. XRD-measurements showed good single-phase qualtiy of CuGaSe_2. TRMC-measuremetns reveal an increase of the hole mobiltiy of Ag-doped material compared to undoped CuGaSe_2.