Increased homogeneity and open-circuit voltage of Cu(In,Ga)Se2 solar cells due to higher deposition temperature

Cu(In,Ga)Se2-absorber deposition on commonly used soda lime glass is constrained in temperature by the softening of the substrate. To overcome this limitation, a high-temperature resistant glass was employed as a substrate for the growth of Cu(In,Ga)Se2-absorbers by multi-stage coevaporation at standard (530 °C) and elevated (610 °C) temperatures. Absorbers were investigated using cathodoluminescence and X-ray diffraction and compared to the performance of solar cells fabricated from these absorbers. The higher deposition temperature is shown to lead to an increased homogeneity of the absorber layer both laterally and vertically and strongly enhanced open-circuit voltage. A best certified efficiency of 19.4% is reached.