Indium Tin Oxide-Free Polymer Solar Cells: Toward Commercial Reality - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 185

Indium Tin Oxide-Free Polymer Solar
Cells: Toward Commercial Reality

Dechan Angmo, Nieves Espinosa and Frederik Krebs

Abstract Polymer solar cell (PSC) is the latest of all photovoltaic technologies
which currently lies at the brink of commercialization. The impetus for its rapid
progress in the last decade has come from low-cost high throughput production
possibility which in turn relies on the use of low-cost materials and vacuum-free
manufacture. Indium tin oxide (ITO), the commonly used transparent conductor,
imposes the majority of the cost of production of PSCs, limits flexibility, and is
feared to create bottleneck in the dawning industry due to indium scarcity and the
resulting large price fluctuations. As such, finding a low-cost replacement of ITO
is widely identified to be very crucial for the commercial feasibility of PSCs. In
this regard, a variety of nanomaterials have shown remarkable potential matching
up to and sometimes even surpassing the properties of ITO. This chapter elabo-
rates the recent developments in ITO replacement which include, but are not
limited to, the use of nanomaterials such as metal nanogrids, metal nanowires,
carbon nanotubes, and graphene. The use of polymers and metals as replacement
to ITO is introduced as well. Finally, recent progress in large-scale experiments on
ITO-free PSC modules is also presented.

1 Introduction

The impacts of global warming are increasingly becoming evident in the form of
intensifying weather calamities, disappearing glaciers, and increasing water levels
in the oceans. Such a scenario has the world gearing toward ''green'' energy
technologies. Photovoltaic cells or solar cells convert sunlight directly into elec-
tricity and is one of the many classes of green technologies. Silicon-based solar