Selenium treatment on the polycrystalline CuIn1−xGaxSe2 thin films sputtered from a quaternary target

In this work, selenium treatment at 250-350°C on the polycrystalline CuIn1-xGaxSe2 (CIGS) thin films sputtered from a quaternary target has been investigated in order to passivate anionic defects which induce the current-blocking behavior and lowering open circuit voltage. The CIGS thin films were selenized in a closed-space graphite container. The result of selenization was characterized by Raman spectroscopy, EQE and the current-voltage-temperature measurement. After selenization at 350°C, the current-blocking behavior is inhibited and Voc increases from 310mV to 640mV. Until now, the efficiency near 9% can be obtained by an optimized selenization process.