Researchers at NREL have developed a new approach for solution deposition of hybrid organic-inorganic lead halide perovskite films that greatly improve the performance and stability of photovoltaic devices. The process, called self-seeding growth (SSG), involves the multi-step application of a formamidinium methylammonium cesium (FA/MA/Cs) perovskite precursor solution that, until now, has typically been applied in only one step. Instead of an annealing step, consecutive applications of perovskite precursor inks to a substrate with intermediate antisolvent treatments, demonstrate a “seeding” effect where previous application steps help produce a subsequent perovskite film with far fewer defects and significantly improved grain morphology. In this process, the consecutive SSG application may be repeated one to four times before finally annealing the perovskite layer under high heat. The resulting thin film layer yields improved structural and optoelectronic properties and consistently boosts power conversion efficiency into the 20 percent range.
When compared to standard one-step solution-deposited devices, SSG devices exhibit reduced defect densities, improved charge-carrier transport and lifetime, fewer apparent grain boundaries, and enhanced properties of hydrophobicity for sustained retention of power conversion efficiency within humid ambient conditions. Furthermore, the SSG process is not limited to only the FA/MA/Cs chemical composition detailed above, but can also be applied with different substrates, solvents, and perovskite compositions, thus making it a tremendous new method for preparing stable, high-quality perovskite thin films for photovoltaic device applications.
This technology is within the Unique Perovskite Deposition Processes and Perovskite Film Stability groups of NREL’s perovskite portfolio. For further information regarding NREL's broader perovskite portfolio, please visit NREL's Perovskite Patent Portfolio website here.
Or please contact Bill Hadley at: Bill.Hadley@nrel.gov
Applications and Industries
- Improved perovskite structure stability.
- Enhanced hydrophobicity in device structure design.
- Increased durability over devices that employ one-step precursor applications.