The Active Role of Ultrathin Perovskite Monocrystals in the Development of High-efficiency Solar Cells

Recently, scientists from the Changchun Institute of Optics and Mechanics of the Chinese Academy of Sciences have prepared a high-quality halide perovskite-type single crystal by combining anti-solvent gas phase assisted crystallization and space confinement strategies, and prepared a highly efficient perovskite solar cell based on this material.

Perovskite solar cells are solar cells that use perovskite-type organic metal halide semiconductors as light-absorbing materials. In the development and research of solar cells, the halide perovskite single crystal solid has large crystal grains, small grain boundaries and uniform surface morphology, which can improve charge transfer and collection, and suppress recombination losses. It is considered to be the ideal for realizing high-efficiency solar cells . Nevertheless, the preparation of high-quality thin single crystals (TMCs) for solar cells is still a major challenge in the research and development of new energy materials.

Researchers used trichloroethane (TCE) as an anti-solvent and prepared methylammonium lead iodide (MAPbI₃) perovskite by AVC method at a temperature of 70 °C. Then, using PEDOT:PSS spin-coated ITO/glass as the substrate, a weight-controllable silicon dioxide cover layer was used to adjust the thickness of the perovskite thin single crystal, and a millimeter-level methylammonium lead iodide (MAPbI₃) was synthesized. ) The thickness of perovskite thin single crystal can be controlled between tens of nanometers to several microns.

The solar cells based on these MAPbI₃ TMCs show power conversion efficiency (PCE) of 20.1% which is significantly improved compared to their polycrystalline counterparts (PCE) of 17.3%. The MAPbI₃ TMCs show large grain size, uniform surface morphology, high hole mobility (up to 142 cm2 V⁻¹ s⁻¹), as well as low trap (defect) densities. These properties suggest that TMCs can effectively suppress the radiative and nonradiative recombination loss, thus provide a promising way for maximizing the efficiency of perovskite solar cells.

Reference: Wenchi Kong, et al, Ultrathin Perovskite Monocrystals Boost the Solar Cell Performance, Adv. Energy Mater. 2020, DOI: 10.1002/aenm.202000453