Two-Dimensional Colloidal Quantum Wells for Future Photonic Sources


Event details

Date 31.10.2019
Hour 16:0017:00
Speaker Prof. Chih-Jen SHIH
Department of Chemistry and Applied Biosciences
ETH Zurich
Category Conferences - Seminars
ChE-606 - Highlights in Energy Research seminar series
Miniaturized photonic sources based on semiconducting two-dimensional (2D) materials offer new technological opportunities beyond the modern III-V platforms. For example, the quantum-confined 2D electronic structure aligns the exciton transition dipole moment, directing emission perpendicular to the surface which gives rise to high-efficiency quantum optics and electroluminescent devices. It requires scalable materials and processes to create the decoupled multi-quantum-well (MQW) superlattices, in which individual 2D material layers are isolated by atomically thin quantum barriers (QBs). My research group developed synthetic routes to obtain monodispersed, quantum-confined colloidal quantum wells (CQWs) of lead halide perovskites with precise thickness control, yielding different emission colors without altering the chemical composition. We successfully developed the protocols fabricating the thin-film MQW superlattices out of these materials. Unexpectedly, an enhancement of PLQY with respect to colloidal dispersions was observed, and individual QWs can be decoupled with unprecedentedly ultrathin QBs that screen interlayer interactions within the range of 6.5 Å. These unique phenomena were investigated in order to uncover the underlying physical mechanisms. The photonic sources demonstrated here have narrowband emission together with high quantum yield, directionality, and wavelength tunability, which are highly desirable for many near-field and far-field applications such as nanoantennas and light-emitting diodes.

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