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Graphene–Ruthenium Complex Hybrid Photodetectors with Ultrahigh Photoresponsivity
Author(s) -
Liu Xien,
Lee Eun Kwang,
Oh Joon Hak
Publication year - 2014
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201400403
Subject(s) - responsivity , photodetector , materials science , graphene , optoelectronics , photoconductivity , ruthenium , doping , monolayer , absorption (acoustics) , charge carrier , nanotechnology , chemistry , biochemistry , composite material , catalysis
The maximum responsivity of a pure monolayer graphene‐based photodetector is currently less than 10 mA W −1 because of small optical absorption and short recombination lifetime. Here, a graphene hybrid photodetector functionalized with a photoactive ruthenium complex that shows an ultrahigh responsivity of ≈1 × 10 5 A W −1 and a photoconductive gain of ≈3 × 10 6 under incident optical intensity of the order of sub‐milliwatts is reported. This responsivity is two orders of magnitude higher than the precedent best performance of graphene‐based photodetectors under a similar incident light intensity. Upon functionalization with a 4‐nm‐thick ruthenium complex, monolayer graphene‐based photodetectors exhibit pronounced n‐type doping effect due to electron transfer via the metal−ligand charge transfer (MLCT) from the ruthenium complex to graphene. The ultrahigh responsivity is attributed to the long lifetime and high mobility of the photoexcited charge carriers. This approach is highly promising for improving the responsivity of graphene‐based photodetectors.