Nanocrystal Skins with Exciton Funneling for Photosensing

Abstract

gration atop electronic substrates (e.g., using dip coating, spin coating and drop casting), where lattice mismatch problems do not arise. Therefore, these NCs are promising candidates for applications in diverse areas, such as in light-emitting diodes, [ 3 ] solar cells, [ 4 ] and photodetectors [ 5 ] as well as for biolabeling [ 6 ] and biosensing. [ 7 ] Conventional photodetectors using NCs typically operate on the principle of collecting photogenerated charges, where an external bias must be applied for the charge collection. Although photodetectors comprising a Shockley-Schottky barrier can in principle be operated without an applied bias (in the open circuit mode), this would commonly come at the cost of decreasing the sensitivity. Recent research efforts increasingly focus on NC photodetectors that show a remarkable level of sensitivity [ 8 ] and short response times. [ 9 ] These photodetectors do, however, rely on photocurrent collection and commonly exhibit high dark current, which results in high noise levels and limits the device's detection capabilities. [ 10 ] As an alternative photosensor architecture, NC skins offer the potential of high sensitivity for large-area applications because they operate on the principle of photogenerated voltage buildup in the absence of an external bias. With a single NC layer in the device structure, noise generation is signifi cantly reduced, which enhances the device sensitivity. [

In Situ Fabrication of Vertical Multilayered MoS2/Si Homotype Heterojunction for High-Speed Visible-Near-Infrared Photodetectors

“…Moreover, we estimated the responsivity ( R ) and photogain ( G ), which are critical parameters related to the photodetector sensitivity and can be expressed as:where I p is the photocurrent, P opt is the light intensity power irradiated on the device, η is the external quantum efficiency, h is the Planck's constant, c is the velocity of light in vacuum, q is the electronic charge, and λ is the exciting wavelength . Based on above Equation , the R and G can be estimated to our 11.9 A W –1 and 22.73 under illumination (650 nm, 90 mW cm –2 at bias of –2 V) by assuming η = 1 for simplicity, which is comparable to the values for many previous MoS 2 ‐based photodetectors and some quantum dots photodetectors . The corresponding wavelength‐dependent responsivity was shown in Figure S6, Supporting Information.…”

Fabrication of Ultrathin Bi2S3 Nanosheets for High‐Performance, Flexible, Visible–NIR Photodetectors

“…However, the electrical performance (e.g., carrier mobility) of the quantum dots (QDs) film is limited due to the sever scattering from a very large number of grain boundaries within the QDs film due to the nanoscale grain size. Moreover, one‐dimensional (1D) material suffers from incomplete surface coverage . So, the ultrathin 2D nanostructures are more conducive to satisfy the requirements of ultrathinness, low‐cost, portability, and mechanical stability in high performance flexile optoelectronic devices …”

TiO<inf>2</inf> assisted sensitivity enhancement in photosensitive nanocrystal skins

“…Furthermore, NC monolayer of the LS-NS makes the device semi-transparent with sufficient absorption, while reducing the noise generation and dark current. In our other recent work, we also reported that, by using a thick photoactive NC layer, a much lower photovoltage buildup was observed in the LS-NSs and it was attributed to the self-absorption effect [4]. In addition, we demonstrated the sensitivity increase in the LS-NSs via the absorption enhancement of NC film with the integration of plasmonic nanoparticles [5].…”