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

Abstract

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.