Scientists synthesize color-changing semiconductor material

Semiconductor materials known as 2D halide perovskites can be used in devices such as solar cells and light-emitting diodes. Scientists led by Associate Professor Nouripan Matthews from NTU’s School of Materials Science and Engineering have synthesized four unique types of 2D halide perovskites.

The results of this study will be published in the Journal of the American Chemical Society.

Dr. Ayan Dzumekenov, a researcher at the school and lead author of the study, created the new perovskites using a novel approach that incorporates the non-toxic solvent dimethyl carbonate into methylammonium-based perovskite crystals.

By analyzing the new crystal structure, scientists discovered that by adjusting the ratio of methylammonium to dimethyl carbonate in the structure, they could tune the structure’s bandgap. The bandgap, which determines the color of a material, is the energy required for electrons to be released from a bonded state and become conductive.

The ability to tune the width of the bandgap is important for various applications of perovskites. The new 2D halide perovskites also exhibit dynamic “switchable” behavior.

The researchers discovered that one of the perovskites can switch between two color states, changing from orange to red when heated to 80 degrees Celsius, and back to its original color when cooled to room temperature.

Scientists demonstrated that the color change reaction was repeated for 25 cycles. This thermochromic switching phenomenon opens the door to applications such as smart coatings and thermal inks that change color at different temperatures.

The scientists hope their innovation will pave the way for technological applications of 2D halide perovskites in optoelectronics and other fields.