Highly-flexible and -stable deep-ultraviolet photodiodes made of graphene quantum dots sandwiched between graphene layers

摘要

We first report highly-flexible and -stable deep-ultraviolet (DUV) photodiodes (PDs) by employing graphene (GR) quantum dots (GQDs) sandwiched between top/bottom GR layers on polyethylene terephthalates (PETs). Here, 3-aminopropyl triethoxysilane is inserted between the bottom GR and the PET substrate to enhance the bending stabilities without degradation or delamination by the chemical bonding. GQDs of similar to 5 nm diameter are proved to be well formed on the bottom GR by various structural and optical analysis tools including high-resolution transmission electron microscopy, Raman scattering, and photoluminescence. The DUV PDs exhibit 10 photo-/dark-current ratio, 0.1 AW(-1) responsivity (R), and 1.1 x 10(13) cm Hz(1/2)/W detectivity at a wavelength of 254 nm. In addition, the R is reduced by only 13% even after 1000-times repeated bending tests at a bending curvature of 4 mm, and is almost consistent during the operations for 1000 h under ambient conditions.