Fabrication of Perovskite Solar Cells with Digital Control of Transparency by Inkjet Printing

Semitransparency
is an attractive and important property in solar
cells since it opens new possibilities in a variety of applications
such as tandem cell configuration and building-integrated photovoltaics.
Metal halide perovskite has the optimal properties to function as
the light harvester in solar cells and can be made as a thin film,
while its chemical composition can change its band gap. However, achieving
high transparency usually compromises the solar cell’s efficiency.
Here we report on a unique approach to fabricating semitransparent
perovskite solar cells that does not rely on their composition or
their thickness. The approach is based on a scalable process, inkjet
printing of arrays of transparent pillars, which are composed of inert
photopolymerizable liquid compositions and are partly covered by the
perovskite. This material can be printed at specific locations and
array densities, thus providing a digital control of both the transparency
and efficiency of the solar cells. The new semitransparent device
structure shows 11.2% efficiency with 24% average transparency without
a top metal contact. Further development including deposition of a
transparent contact enabled the fabrication of fully semitransparent
devices with an efficiency of 10.6% and average transparency of 19%.