Photoelectrochemical Cell

A photoelectrochemical cell (PEC) is a device that converts solar energy (light) into chemical energy or electricity. It typically consists of components such as a photoactive semiconductor working electrode (photoanode or photocathode), a counter electrode, and an electrolyte. The key operating principle involves irradiating the photoactive semiconductor with light, which generates electron-hole pairs when the light energy is equal to or greater than the semiconductor's bandgap.

In PECs that produce electrical energy, photogenerated electrons are conducted through the semiconductor to an external circuit, similar to dye-sensitized solar cells. For PECs that drive chemical reactions, the excited electrons and holes participate in reactions such as water splitting, where hydrogen and oxygen gases are produced from water using sunlight. The holes oxidize water at the photoanode, and the electrons reduce protons to hydrogen at the cathode.

There are two main types of photoelectrochemical cells:

PECs produce electrical energy, functioning like photovoltaic cells.

Photoelectrolytic cells, which use light to drive chemical reactions, such as splitting water to generate hydrogen fuel.

Important material criteria for PECs include a suitable bandgap for solar absorption, conductivity for charge transport, appropriate band positions for redox reactions, catalytic activity, stability, low cost, and earth abundance.

PECs have promising applications in clean energy, including hydrogen fuel production via water splitting, CO2 reduction to fuels like methane, and advanced solar cells such as dye-sensitized and perovskite solar cells.

Common PEC configurations include glass and PTFE cells, with options for two- or three-electrode setups for different experimental or practical needs.

photoelectrochemical cells harness sunlight to generate electrical power or valuable chemical fuels, playing a significant role in renewable energy technologies.