A research team from Florida State University has discovered a new method for generating blue light from a family of materials that has tremendous potential for optoelectronic devices, such as solar cells, light-emitting diodes (LEDs), and lasers.
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The team, led by Biwu Ma, a professor of chemistry at Florida State University, has just published new research in Advanced Energy Materials that outlines a simple method for producing steady and effective blue light from metal halide perovskites.
A new class of semiconductor materials known as metal halide perovskites features a cubic crystal structure, good light-emitting characteristics, and is simple and inexpensive to produce.
Perovskite-based LEDs for green and red light have already been developed by scientists, including Ma, but efficient and steady blue light has proven more challenging. Blue light uses a lot of energy, and its quality frequently degrades over time.
White light cannot be produced without an effective and reliable blue light.
We developed new strategies to achieve efficient and stable blue light from perovskites and fabricate LEDs with higher performance. If you want a full color display, you need blue, green and red. Green and red have a good performance already, but blue is harder. It is not easy to make a stable blue because it has higher energy.
Biwu Ma, Professor, Chemistry, Florida State University
With the help of a metal halide perovskite based on the chemical substance cesium lead bromide or CsPbBr3, Ma and his colleagues were able to produce blue-emitting nanoplatelets. The effects of strong dielectric and quantum confinement are present in nanoplatelets since they are nanomaterials with only a few unit cells in thickness.
Biwu Ma is a professor of chemistry at Florida State University. Image Credit: Florida State University.
These specific nanoplatelets were coated with a multifunctional organic sulfate that allowed for surface passivation, a highly efficient technique used to improve luminescence qualities and stability, to make them emit efficient and stable blue light.
In this study, simple organic sulfate passivation aids in preventing the degradation of the nanoplatelets, enabling them to emit a more effective and stable blue light.
Proof-of-concept LEDs were made to emit pure blue light with a peak at 462 nm using these surfaced passivated CsPbBr3 nanoplatelets as emitters.
One of the greatest values for pure blue perovskite LEDs based on nanoplatelets is the luminance of 691 candelas per square meter (the standard unit that indicates the brightness of a device) and the half-lifetime of 20 minutes obtained in this work.
Ma added, “Our work clearly shows the potential of using properly surface passivated perovskite nanoplatelets as emitters for highly efficient and stable LEDs.”
The National Science Foundation and the FSU Office of Research provided funding for this study.
Graduate student He Liu, postdoctoral fellow Animesh Mondal, graduate students Tunde Shonde, Maya Chaaban, Sujin Lee, Azza Ben-Akacha, Oluwadara Olasupo, and Fabiola Gonzalez, as well as research facility managers J.S.R. Vellore Winfred, Xinsong Lin, and Yan Xin, all from Florida State University, made contributions to this work.