A Combination of Silver Nanowires and Al2O3 to Replace ITO and MgF2 in a Cu(In,Ga)Se2 Thin‐Film Solar Cell

Abstract Silver nanowire (AgNW) transparent conducting electrodes can be prepared via a low‐cost process and deliver optoelectronic performance comparable to or even better than that of indium tin oxide (ITO). However, their integration into a real device is challenging, mainly because of the weak adhesion between AgNWs and the underlayer. Furthermore, when AgNWs replace ITO, a different material needs to be considered for the antireflection coating (ARC) of a thin‐film solar cell. A combination of AgNWs and Al 2 O 3 is employed to replace both ITO and the MgF 2 in a Cu(In,Ga)Se 2 (CIGS) thin‐film solar cell. The quality of the contact between the AgNWs and CdS buffer is improved by introducing a chemical‐bath‐deposited welding layer, which improves the fill factor of the cell from 43.4% to 68.7%. Accordingly, the exposed surface of the CIGS thin‐film solar cell changes from ITO to CdS. Therefore, the commonly used MgF 2 ARC is replaced with Al 2 O 3 , which is a better match in terms of the refractive index for AgNW‐based CIGS thin‐film solar cells. The adoption of the Al 2 O 3 ARC increases the short‐circuit current density of the cell by 7.3%. In conclusion, a device structure of Al 2 O 3 /AgNW/CdS/CIGS/Mo is suggested for CIGS thin‐film solar cells.