Current Photovoltaic Research ISSN:2288-3274(Print) 2508-125X(Online)

Minority carrier diffusion length is one of the most important parameters of solar cells, especially for short circuit current density (Jsc). In this report, we proposed the calculating method of the minority carrier diffusion length (L_n) in CIGS solar cells through biased quantum efficiency (QE). To verify this method's reliability, we chose two CIGS samples which have different grain size and calculated L_n for each sample. First of all, we calculated out that L_n was 56nm and 97nm for small and large grain sized-cell through this method, respectively. Second, we found out the large grain sized-cell has about 7 times lower defect density than the small grain sized-cell using drive level capacitance profiling (DLCP) method. Consequently, we confirmed that L_n was mainly affected by the micro-structure and defect density of CIGS layer, and could explain the cause of Jsc difference between two samples having same band gap.