Ultrathin Cu(In,Ga)Se2 solar cells with Ag-based reflective back contacts

We developed a highly reflective back contact for Cu(In,Ga)Se2 solar cells based on silver encapsulated in a TCOs stack, compatible with substrate configuration. We demonstrated ultrathin (500 nm) Cu(In,Ga)Se2 solar cells with 13.5% efficiency and state-of-the-art J(SC)= 28.9 mA/cm2, 2.7 mA/cm2 more than the reference cell on molybdenum. We also demonstrated a 530 nmthick (Ag,Cu)(In,Ga)Se2 solar cell on Mo with state-of-the-art efficiency (14.9%) and remarkably high VOC (741 mV) and FF (81.8%). This result coupled with a highly reflective back contact for improved JSC, has the potential for a 500 nm-thick (Ag,Cu)(In,Ga)Se2 solar cell with an 18% efficiency.