In the quest for more efficient and stable solar energy solutions, researchers have been fine-tuning the microscopic details of thin-film solar cells, and a recent study has shed new light on the role of heat treatment in enhancing the performance of a crucial component. Dr. Fazliyana ‘Izzati Za’abar from Universiti Kebangsaan Malaysia and her team have published their findings in the Journal of Science: Advanced Materials and Devices (translated as Journal of Science: Advanced Materials and Devices), offering insights that could significantly impact the commercial viability of thin-film photovoltaic technologies.
The study focuses on chalcopyrite Cu(In,Ga)Se2 (CIGSe) solar cells, which have already demonstrated impressive potential, with record efficiencies of 23.6% in solar cells and 19.2% in commercial modules. However, these cells still face challenges related to optical losses, parasitic effects, and recombination, which limit their overall efficiency and stability.
At the heart of the research is the molybdenum (Mo) thin film, a critical back-contact layer in CIGSe solar cells. The team investigated the effects of in-situ substrate heating and selenium-free annealing on the growth of the MoSe2 interlayer, which forms during the deposition process. “We found that heat treatment during and after the deposition process plays a pivotal role in improving the microstructure of Mo films,” explained Dr. Za’abar. “This, in turn, enhances the electrical performance and interfacial properties of the back-contact layer.”
The researchers discovered that substrate heating and in-situ annealing during the direct current (DC) sputtering of Mo thin films led to significant improvements in film crystallinity, minimization of microstrain, and decreased dislocation density, particularly in the (110) crystal orientation. These enhancements contributed to better electrical resistivity, a key factor in the overall efficiency of solar cells.
Interestingly, the study also revealed that films annealed at 500°C exhibited unexpectedly long, fibrous grain structures with porosity. “This was contrary to what we initially predicted,” noted Dr. Za’abar. “It highlights the complex nature of heat treatment and its nuanced effects on the microstructure of Mo films.”
The findings underscore the importance of optimizing the microstructural growth of Mo films to boost the stability and efficiency of CIGSe-based solar systems. As the energy sector continues to seek more efficient and cost-effective solar technologies, this research offers valuable insights that could drive further advancements in thin-film photovoltaics.
Dr. Za’abar’s work, published in the Journal of Science: Advanced Materials and Devices, not only contributes to the scientific understanding of Mo thin films but also paves the way for practical applications that could enhance the commercial impact of CIGSe solar cells. By fine-tuning the deposition and annealing processes, manufacturers may soon achieve higher efficiencies and longer lifespans for their solar modules, ultimately making solar energy more accessible and affordable for a broader range of applications.
As the world transitions towards renewable energy sources, innovations like these are crucial. The energy sector stands to benefit significantly from continued research into the fundamental properties of materials used in solar cells, ensuring that the technology evolves in tandem with the growing demand for clean, sustainable energy.