Researchers at the Yale School of Engineering & Applied Science have discovered a modification to perovskite solar cells, which could lead to a new generation of more efficient solar cells.
Perovskite, a mineral discovered in the Ural Mountains of Russia in the 1830s, has in recent years become the rising star in the field of solar energy. Able to absorb a broad range of the light spectrum, and with properties that allow the carrier to be transferred over a comparatively long distance, perovskite has given solar cells the potential for very high power conversion efficiencies.
“The only thing is, it’s not very stable and it doesn’t maintain that efficiency for any appreciable amount of time,” said Andre Taylor, associate professor of chemical & environmental engineering. In his Transformative Materials & Devices lab, researchers have found a solution with dimethyl sulfoxide (DMSO), an organic solvent that can add stability and efficiency to perovskite solar cells (PSCs). The results of their work are published in Nanoscale.
A perovskite solar cell is made of numerous layers, including the hole transport layer (HTL), which is critical to bringing charge carriers from the active layer of perovskite to the cell’s electrodes. A polymer mixture known as PEDOT:PSS is the most commonly used material for HTLs, but its low conductivity makes it inefficient.
Placing a thin layer of DMSO on the HTL, however, can significantly help reduce the flaws of the PEDOT:PSS material, said Di Huang, lead author of the study. With the DMSO treatment, the researchers were able to boost the devices conversion efficiency to 16.7% – a 37% improvement over the research group’s control device. The properties of DMSO, she said, provide a better mobility of HTL for charge transportation. It also helps the perovskite thin films to grow the larger grains with increased crystallinity.
Huang, a Ph.D student at Beijing Jiaotong University, and currently a visiting assistant in research (VAR) in Taylor’s Lab, said there are ways to further improve the performance of the PSC with modifications to the device’s other layers. For instance, improvements to the perovskite layer itself – using different solvent techniques and different crystallization techniques – could go a long way toward that end.
Publication: Di Huang, et al., “Perovskite solar cells with a DMSO-treated PEDOT:PSS hole transport layer exhibit higher photovoltaic performance and enhanced durability,” Nanoscale, 2017; doi:10.1039/C6NR08375G