Photovoltaics (PVs) show high conversion efficiency in renewable energy. However, PV systems demand advanced
preparations and relatively large amounts of staring materials. Photoelectrochemical (PEC) systems, with
monolithic semiconductor (SC) electrode/Redox couple interface, emerged, but still demand special preparation
conditions and relatively large amounts of starting materials. Polycrystalline film electrodes, are studied as
replacement for monolithic SC electrodes, both theoretically and experimentally. Examples are dye-sensitized
solar cells (DSSCs) and metal chalcogenides. With narrow-to-medium band gaps, metal chalcogenides are suitable
for the abundant visible solar light. However, polycrystalline film electrodes suffer major shortcomings.
Pristine films show low conversion efficiency. Being polycrystalline, they have low carrier mobility. They are
also unstable to photo-corrosion, due to charge build-up in the space charge layer (SCL). Enhancement of
polycrystalline film electrode PEC performance and stability was reported using different methods. Among
those, charge transfer catalysis at the film electrode surface, is focused here. The modification involves attaching
electroactive species to the electrode surface. Ability of electroactive species to behave as charge transfer catalysts
at the solid/liquid interface is discussed. By such behavior, the catalysts speed up charge transfer and
consequently increase photocurrent. Moreover, charge build-up in the SCL is prevented by quick charge transfer,
which protects the electrode surface from photo-corrosion. Ability of charged electroactive species to shift flat
band edge position, with its consequences, is also described. Recommended features of an effective catalyst
species for PEC systems are described together with recommendations for more future research in the field.

Title

Solar Energy

Publisher

ELSEVIER

Publisher Country

United States of America

Indexing

Thomson Reuters

Impact Factor

5.17

Publication Type

Both (Printed and Online)

Volume

197

Year

2020

Pages

12