07 May 2012 Hybrid Graphene-Quantum Dot Phototransistors with Ultrahigh Gain

Artistic representation of the device consisting of graphene with quantum dots on top

ICFO research groups report in Nature Nanotechnology on photodetection advances combining nanocrystals and graphene. The research groups at ICFO led by Professors Gerasimos Konstantatos and Frank Koppens, both NEST Fellows, announce in Nature Nanotechnology the development of a novel hybrid photodetector that is ultra-sensitive to visible and infrared light. The device is made of graphene, an ultra-thin, flexible conductor of electricity, and nanocrystals (colloidal quantum dots), semi-conducting nanomaterials which can be tuned to absorb a wide range of wavelengths. This graphene-nanocrystal combination has led to the production of a device which is a billion times more sensitive than existing graphene photodetectors to date.

This discovery will have far reaching implications in the development of ultra-sensitive, low-cost photodetectors with a wide range of imaging applications, including biomedical imaging and night vision, as well as remote sensing and metrology. The reported hybrid device consists of low-cost materials that can be integrated with existing silicon technologies, and can be readily deposited onto any sort of substrates- rigid or flexible, crystalline or amorphous. The search for low-cost, ultra-sensitive photodetectors, in particular for light that is not visible with the naked eye (such as infrared light) has been a pressing challenge for physicists and engineers.