21.09% Efficiency For Perovskite Solar Cells

Researchers at King Abdullah University of Science & Technology (KAUST) have announced achieving a power conversion efficiency of 21.09% for perovskite single-crystal solar cells. To reach this stage, they used high-aspect ratio, single-crystal films of methylammonium lead-triiodide perovskites instead of existing polycrystalline thin films.

Terming polycrystalline thin films used in existing perovskite solar cells as highly disordered and defective and restricting the device from achieving optimal performance, KAUST’s team produced the new crystal films by starting the crystallization between 2 polymer-coated substrates which they said would physically restrict crystal growth to 1 dimension under heating.

Researchers Omar Mohammed and Osman Bakr found that single-crystal perovskites manifest substantially lower defect density and much higher charge-carrier diffusion lengths. This allows them to keep light-generated electrons separate from positively charged holes and create electrical current.

“We reasoned that these single crystals offer a chance for perovskite solar-cell technology to overcome these limitations and get as close as possible to the theoretical efficiency limit,” said Mohammed.

The researchers stress that this efficiency highlights the potential role of single crystals in the development of perovskite-containing devices in parallel with the path taken by their polycrystalline counterparts. Their research, they claim, generates homogenous and defect-free crystals that could fast-track the commercialization of perovskite solar cells.

The research was published in the ACS Energy Letter of ACS Publications.