This report describes how the project has been developing high performance semiconductor materials to be used in robust and efficient systems to produce hydrogen directly from solar energy.
The aim of this project is to address the issues which hinder the potential of III-V semiconductors for photoelectrochemical (PEC) hydrogen generation, namely their high cost and poor stability. Indeed, although they enable the highest energy conversion efficiencies, III-V-based PEC systems typically involve sophisticated growth techniques, expensive co-catalyst materials and short lifetimes.
Overcoming these challenges is crucial to promote the commercial prospects of solar hydrogen systems, which have been identified as a key element to the energy transition.
Although the requirement to grow III-V semiconductors by complex epitaxial techniques is hardly avoidable, some research directions have emerged in the last years to reduce the balance of costs of these PEC systems.
- The optimisation of the electronic structure with the use of multijunction cells could lead to increased solar-to-hydrogen (STH) efficiencies to counterbalance the fabrication costs.
- Efforts are invested in the development of substrate recycling methods for these expensive materials. In particular, the spalling lift-off technique has shown promising preliminary results.
- The search for earth-abundant alternatives to noble metal-based co-catalysts is a very active area of research.
- The investigation of efficient passivation techniques to improve the stability (hence durability) of PEC systems is continuously enriched with the optimisation of thin-films deposition techniques.