Organic semiconductors are on their way to clean hydrogen production

28 November 2022 | At EPFL in Switzerland, Kevin Sivula’s research group LIMNO (Laboratory for Molecular Engineering of Optoelectronic Nanomaterials) is developing new materials and systems for direct photoelectrochemical (PEC) and heterogeneous photocatalytic (PC) hydrogen production via solar-driven water splitting. Viable PEC and PC solar fuel production on a global scale requires the development of systems with simplicity, stability, and high efficiency. LIMNO works to advance the field of PEC and PC solar hydrogen production by developing specific classes of promising semiconducting materials (e.g. transition metal dichalcogenides, organic semiconductors, and metal oxide semiconductors), and system strategies (e.g. tandem cells, photoelectrode membrane assemblies, nanoparticle dispersions). In addition, LIMNO’s research focuses on understanding and improving the operation of overall material systems via interface engineering and advanced operando characterization techniques to gain insight into charge transport and transfer/catalysis processes.

Most recently, Sivula’s group published new results in Advanced Energy Materials, reporting major advances in the photoelectrochemical splitting of water into H₂ and O₂ using organic semiconductors.

PEC cells employing organic semiconductors (OS) are promising considering their composition from widely available carbon-based components, but despite encouraging advances with the half reactions, complete overall water splitting has remained a challenge. In this new report, the LIMNO group describes two advances they made with the organic semiconductor photocathode (semiconductor tuning and employing a self-assembled monolayer modified substrate) to afford robust photocathode operation under alkaline pH. These advances allowed the first demonstration of unassisted solar water splitting with a photoelectrochemical tandem cell employing organic semiconductors.

“Our demonstration is a first step to validate the OS-based PEC tandem cell and further research will advance this technology toward practical application”, says Kevin Sivula.