Na확산과 Ga첨가에 따른 동시증발법으로 제조된 CIGS박막과 CdS/CIGS 태양전지 특성

Abstract

We prepared and characterized Cu(In_1-xGa_x)Se₂(CIGS) films using a elemental co-evaporation method for absorbing layer of high efficiency thin film solar cells. The CIGS films deposited on a soda-lime glass exhibited low resistivity because of higher carrier concentration. Na was accumulated at the CIGS surface and the 0 and Se were also accumulated at the surface, suggesting that oxidation is a driving force of Na accumulation. The structure of CIGS film was modified or a secondary phase was formed in the Cu-poor CIGS bulk films probably due to the incorporation of Na into Cu vacancy sites. As the Ga/(In+Ga) ratio increased, the diffraction peaks of CU_0.91(In_1-xGa_x)Se₂films were shifted to larger angle and splitted, and the grain size of Cu_0.91(In_1-xGa_x)Se₂films became smaller. All CU_0.91(In_1-xGa_x)Se₂films showed the p-type conductivity regardless of the Ga/(In+Ga) ratio. Ag/n-ZnO/i-ZnO/CdS/CU_0.91(ln_0.7Ga_0.3)Se₂/MO solar cells were fabricated. The currently best efficiency in this study was 14.48% for 0.18cm²area (V_oc=581.5 mV, J_sc=34.88 mA, F.F=0.714).