A facile photolithography process enabling pinhole-free thin film photovoltaic modules on soda-lime glass

Abstract

Release of the alkaline (mainly sodium) impurities from the soda-lime glass (SLG) substrate can compromise scaling-up of thin film photovoltaic (PV) devices deposited at high temperatures. This does not only degrade electronic device quality but also results in catastrophic effects such as delamination of the semiconductor thin films. Device scale-up can be further hindered by the pinholes that may exist across the large panel areas, causing serious shunt paths. We demonstrate fabrication of uniform CdTe mini-modules on the SLG using a facile photolithography process. This process effectively suppresses sodium release and prevents film delamination from the substrate whilst plugging the pinholes within the semiconductor p-n junction layers. Mini-module devices with repeatable device response are demonstrated using an industrial laser scribing system operating long (microsecond)-pulses of a green laser for thin film scribing.