Engineers have developed a low-cost way to make efficient, stable perovskite solar cells at commercial scale. 

New studies show a key component of next-generation solar panels can be created without expensive, high-temperature fabrication methods.

Nickel oxide (NiO) is used as an inexpensive hole-transport layer in perovskite solar cells because of its favourable optical properties and long-term stability.

Making high-quality NiO films for solar cells usually requires an energy intensive and high-temperature treatment process called thermal annealing, which is not only costly, but also incompatible with plastic substrates, until now precluding the use of NiO in the proposed manufacture of printed photovoltaics at commercial scale.

However, researchers have now identified a way to create NiO films of sufficient quality in solution and at relatively low temperatures of less than 150 degrees Celsius.

The researchers used 4-hydroxybenzoic acid (HBA) or trimethyloxonium tetrafluoroborate (Me3OBF4) ligand-modified NiO nanoparticles and a microfluidic mixer, which promotes high-pressure mixing of low volume liquids, to distribute the nanoparticles evenly prior to depositing them on the substrate.

The chemical process could contribute to the scalable fabrication of inorganic and inexpensive, high-performance films able to be used in the commercial production of flexible solar panels.

The researchers have recorded power-conversion efficiencies of 17.9 per cent and 17.5 per cent respectively in prototype devices, compared to 16 per cent for a previous comparable approach, which lacked the advantages of the ligand exchange and also required a post-processing oxygen-plasma treatment step.

Significantly, the new devices exhibited just a 0.2 per cent reduction in efficiency over an intensive 300-hour testing period, providing a strong indication of their potential suitability for commercial applications.

The results are accessible here.