In a significant stride towards enhancing the scalability and efficiency of emerging energy technologies, researchers have developed a novel method for depositing nickel oxide (NiOx) thin films using spatial atomic layer deposition (SALD). This breakthrough, published in the journal *Applied Surface Science Advances* (translated as *Advances in Applied Surface Science*), could have profound implications for the energy sector, particularly in the production of perovskite solar cells and other transparent electronics.
At the heart of this research is Samuel Porcar, a scientist from the Universitat Jaume I de Castellón in Spain. Porcar and his team have successfully demonstrated the deposition of nanocrystalline NiOx thin films using a relatively new nickel precursor, bis(4-(isopropylamino)pent-3en-2-onato)nickel(II), or [Ni(ipki)2]. This precursor had not been previously explored for the atomic layer deposition (ALD) of NiO.
The significance of this work lies in the use of SALD, a variant of ALD that enables much faster deposition rates, even at atmospheric pressure. “SALD is a game-changer because it allows for much higher throughput compared to conventional ALD processes,” Porcar explains. “This makes it ideal for scalable, low-cost manufacturing of devices.”
The researchers achieved a deposition rate of 1.4 nm/min, which is 2 to 10 times faster than the rates reported for conventional ALD of NiO thin films. This was accomplished within a narrow ALD window between 230 °C and 250 °C, with a growth per cycle (GPC) of 0.023 nm. Remarkably, the growth onset of NiOx starts around only 170 °C, indicating the potential for low-temperature processing.
The deposited films exhibited high transmittance, reaching nearly 97% in the visible spectrum for 55 nm thick films. This property is crucial for applications in transparent electrodes and charge selective layers in perovskite solar cells. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies revealed a high homogeneity of the films, while X-ray diffraction (XRD), Raman spectroscopy, and X-ray absorption spectroscopy (XAS) confirmed the presence of a cubic NiOx crystalline phase.
One of the most compelling aspects of this research is the demonstration of conformal coatings on Ag nanowire networks. “This shows that our process can be used to deposit homogeneous and conformal coatings on complex substrates,” Porcar notes. “This is a critical requirement for many emerging technologies.”
The implications of this research are far-reaching. The ability to deposit high-quality NiOx thin films at low temperatures and high throughput could significantly reduce the cost and improve the scalability of perovskite solar cells and other transparent electronics. As the energy sector continues to seek more efficient and cost-effective solutions, innovations like this one could play a pivotal role in shaping the future of renewable energy technologies.
This research, published in *Applied Surface Science Advances*, marks a significant step forward in the field of thin film deposition and holds promise for a wide range of applications in the energy sector. As the world moves towards a more sustainable future, the work of Porcar and his team could be instrumental in accelerating the adoption of next-generation energy technologies.