Deposition and application of a Mo-N back contact diffusion barrier yielding a 12.0% efficiency solution-processed CIGS solar cell using an amine-thiol solvent system

Delamination and high series resistance due to excessively thick MoSe2 are commonly found in solution-processed CIGS solar cells. This work shows the effective functionality of Mo-N as a back contact barrier against selenium diffusion during high temperature selenization. Mo-N barrier layers are deposited by reactive D.C. magnetron sputtering. The Mo-N barrier layer significantly reduces MoSe2 formation at the Mo/CIGS interface and consequently improves adhesion properties and enhances crystallinity of the CIGS absorber. The power conversion efficiency (PCE) of a spray-coated diamine-dithiol based CIGS solar cell improved from our previously published 9.8% to 12.0% after application of the Mo-N back contact barrier layer.