Highly ordered nano-cone back reflector arrays for ultra-thin high performance CIGS cells

Design variations of our Light and Carrier Collection Management (LCCM) architecture were simulated for ultra-thin CIGS cells. Two back reflector materials (Au and Mo) were used. With a nominal CIGS thickness of 200nm, the Mo LCCM and Au LCCM cells produced 28.7 mA/cm² and 31.9 mA/cm² of J_sc, respectively. This J_sc production by the Mo-backed LCCM cell is comparable to a conventional planar cell with a 1.5 um thick CIGS layer. Importantly, the current/absorber volume ratio for the CIGS LCCM cells and for planar cells with Mo reflectors was examined and found to be as high as 1.1×10⁶ mA/cm³ for LCCM cells versus 1.9×10⁵ mA/cm³ for the corresponding planar cell. Such a dramatic difference significantly impacts the all-important indium utilization as well as cost/watt considerations.