Enhancing Hybrid Quantum Dots/Organic Molecules Sensors Quantum Efficacy using Plasmonic Structures

Hybrid organic/inorganic optoelectronic devices based on quantum dots (QDs) may hold promise to sensitive deterministic sensors, however their major drawback lies in their quantum efficiency (~1%). Plasmonics is a promising new approach to enhance absorption and efficiency of solar cells and optoelectronic devices. Metal nano structures support surface plasmon modes, which are used to couple light into a tight localized point in space and use it in a nano-metric scale environment. An easy, fast cheap method to mass produce plasmonic structure is a deposition of very thin metal layer, in our case gold. In these layers the granularity of the gold creates isolated islands that form a complex plasmonic structure supporting localized surface plasmons. This structure exhibits a wide plasmonic resonance and strong electric fields within the gaps. Those features can be tuned and controlled easily by several treatments like thermal annealing.

We are developing a sensitive single photon detector based on QDs and a field effect transistor. In order to enhance the detector quantum efficiency we use thin layer of gold forming nano-islands plasmonic couplers. We have found that a single monolayer of QDs attached to Au nano-islands layer widen the absorption spectrum and enhance dramatically the quantum efficiency. Close to the plasmonic resonance we observe 15% to 35% enhancement, depending on the overlap between the QD`s energy band-gap and the plasmonic resonance.

matangalanty@gmail.com