With the increasing popularity of clean fuel energy, scientists are looking for new processes to develop sustainable fuel generation. They recently discovered a way to supercharge the engine of clean fuel generation by giving materials a slight twist.
Researchers from the University of Cambridge are advancing affordable light-harvesting semiconductors that power devices for converting water into clean hydrogen fuel that is powered solely by sunlight.
These semiconducting materials known as copper oxides while non-toxic, abundant and inexpensive have historically lagged behind silicon in the semiconductor market due to their poor performance. The technique includes developing copper oxide crystals in a precise orientation that improves the transfer of electric charges through the material resulting in substantially faster and more efficient charge transportation.
Light-harvesting copper oxide photocathodes produced using this approach outperformed previous oxide photocathodes by 70% and had increased stability. Recently published, this research demonstrates the potential of affordable resources to accelerate the transition to sustainable energy sources. Moreover, it can be seamlessly integrated into existing energy infrastructure.
Also, check out this research done by Tohoku University Using Disordered Rocksalt Oxides for Rechargeable Magnesium Batteries.
Challenges and Opportunities in Cuprous Oxide
Despite the promising results, cuprous oxide also known as copper (I) oxide has long been regarded as a low-cost prospective alternative to silicon. However, intrinsic limitations hinder its effectiveness in absorbing sunlight and turning it into electric charge. A significant portion of that charge is lost while limiting the material’s performance.
With respect to this context, Dr Linfeng Pan from Cambridge’s Department of Chemical Engineering and Biotechnology stated “Like other oxide semiconductors, cuprous oxide has its intrinsic challenges. One of those challenges is the mismatch between how deep light is absorbed and how far the charges travel within the material, so most of the oxide below the top layer of material is essentially dead space.”
Also, Professor Sam Stranks, who led the research added, “For most solar cell materials, it’s defects on the surface of the material that causes a reduction in performance, but with these oxide materials, it’s the other way round: the surface is largely fine, but something about the bulk leads to losses. This means the way the crystals are grown is vital to their performance.”
To compete with existing photovoltaic materials, cuprous oxides must be optimized to effectively generate and transmit electric charges consisting of an electron-hole that is positively charged during exposure to sunlight.
Future Directions and their Implications
- One potential optimization approach is to use single-crystal thin films which are thin slices of material with a highly organized crystal structure used in electrical applications. However, conventional production of these films is often complex and time-consuming.
- The researchers successfully produced high-quality cuprous oxide films at ambient pressure and room temperature by using thin film deposition techniques. They were able to shift the crystals into a certain orientation by carefully controlling the growth and flow rates within the deposition chamber. Using high temporal resolution spectroscopic techniques, they detected how the crystal orientation altered the efficiency of electric charge flow within the material.
Dr. Pan added “These crystals are basically cubes, and we found that when the electrons move through the cube at a body diagonal, rather than along the face or edge of the cube, they move an order of magnitude further. The further the electrons move, the better the performance.”
- Experiments on a cuprous oxide photocathode created using this technology demonstrated a performance increase of more than 70% compared to the current electrodeposited oxide photocathode.
Prof. Stranks further stated, “Something about that diagonal direction in these materials is magic. We need to carry out further work to fully understand why and optimise it further, but it has so far resulted in a huge jump in performance.”
“In addition to the improved performance, we found that the orientation makes the films much more stable, but factors beyond the bulk properties may be at play,” Dr. Pan further added.
- The researchers note that despite previous gains additional research and development, efforts are required. Nonetheless, they emphasize the potential importance of this and other material families in aiding the ongoing transition to sustainable energy sources.
To conclude Prof. Stranks highlighted “There’s still a long way to go, but we’re on an exciting trajectory. There’s a lot of interesting science to come from these materials, and it’s interesting for me to connect the physics of these materials with their growth, how they form, and ultimately how they perform”
Source: A simple ‘twist’ improves the engine of clean fuel generation
