The main objective of this project is to design optical switches with a response time < 5 ps, a switching energy < 1 fJ/bit and compatibility with silicon technology to excel in high-speed data processing at low heat dissipation. This will be pursued by combining the chemistry of inorganic, nanocrystalline colloids and organic semiconductor molecules to fabricate thin films of organic-inorganic hybrid nanostructures. Optical switches play a pivotal role in modern data processing based on silicon photonics, where they control the interface between photonic optical fibers used for data transmission and electronic processing units for computing. Data transfer across this interface is slow compared to that in optical interconnects and high-speed silicon transistors, such that faster optical switching accelerates the overall speed of data processing of the system as a whole. By modifying the surface of the inorganic nanocrystals with conductive molecular linkers and self-assembly into macroscopic solid state materials, new electronic and photonic properties arise due to charge transfer at the organic/inorganic interface. The multiple optical resonances in these hybrid materials result in strong optoelectronic interactions with external light beams, which are exploited for converting photonic into electronic signals at unprecedented speed. A key concept here is an activated absorption mechanism, in which the nanocrystals act as sensitizers with short-lived excited states, which are activated by a first optical pump beam. Efficient charge transfer at the organic/inorganic interface temporarily creates additional resonances in the molecular linkers, which may be probed by a second optical beam for as long as the sensitizer is in its excited state. Utilizing nanocrystals with excited state lifetimes < 5ps will reward ultrafast response times to pave the way for novel optical switches and high-speed data processing rates for silicon photonics.
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1. Dye-Sensitized Ternary Copper Chalcogenide Nanocrystals: Optoelectronic Properties, Air Stability and Photosensitivity http://arxiv.org/abs/1903.05037
February 2019 - January 2024
European Research Council (ERC Starting Grant)