Among different alternative energy technologies, thin-film photovoltaics (PVs) are gaining greater acceptance as a clean and sustainable energy at a cost competitive with fossil fuels. One shortcoming of PVs is the associated material and fabrication costs for manufacturing such photovoltaic modules at reasonable efficiency levels. What is needed are improvements in low-temperature, roll-to-roll processes to manufacture thin films.
Thin-film perovskite solar cells are made from a recognized, preferred material with the advantage of full low-temperature solution processability and therefore adaptable to roll-to-roll production yielding flexible products. One of the main challenges with these materials, however, is being able to finely control the film morphology during the deposition and crystallization of the perovskite layer. Processes that can optimize the film’s perovskite layer with large grains are highly desirable for reduced recombination of charge carriers.
Air Force researchers have developed a process to make uniform thin films with micron-size perovskite grains, by using a controlled amount of metal ions in a precursor solution. In one example of this process, large organo-lead halide-based perovskite grains are formed during low-temperature thin film growth by adding sodium ions to the precursor solution in a two-step interdifusion process. This generates films with improved power conversion efficiencies compared with non-sodium thin films.
- All-solution, two-step spin coating process amenable to most plastic substrates
- Low-temperature process
- Process can be used to create a multi-layer perovskite structure
- US patent 9,570,240 available for license
- Potential for collaboration with Air Force researchers