Interfacial Recombination for Fast Operation of a Planar Organic/QD Infrared Photodetector
✍ Scribed by Timothy P. Osedach; Ni Zhao; Scott M. Geyer; Liang-Yi Chang; Darcy D. Wanger; Alexi C. Arango; Moungi C. Bawendi; Vladimir Bulović
- Book ID
- 101416094
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 431 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0935-9648
No coin nor oath required. For personal study only.
✦ Synopsis
Thin fi lms of organic semiconductors and colloidal nanocrystal quantum dots (QDs) have attracted considerable interest for a variety of electronic device applications due to the tunability of their electronic structure as well as the potential for scalable device fabrication across large-area substrates. QDs are especially interesting due to the freedom available to directly engineer their optoelectronic properties by varying the nanocrystal size as well as by chemically modifying QD surfaces with oxidation [ 2 , 3 ] or ligand exchange. Of particular interest is the prospect for QD optical response that extends into the short-wavelength infrared (SWIR) part of the spectrum (wavelengths of λ = 1.0 μ m to 2.0 μ m) with QDs of low-bandgap semiconductors such as PbS and PbSe. This wavelength range is largely inaccessible to organic materials yet is critical to effi cient photovoltaics, night vision, [ 11 , 12 ] biological imaging applications, [ 13 , 14 ] and optical communication. [ 15 , 16 ] Photoconductive photodetectors in a planar geometry (i.e. consisting entirely of semiconducting fi lms deposited over laterally arranged electrodes) are an attractive structure for commercial application due to the potential ease with which they can be directly integrated with conventional detector read-out integrated circuits. [ 17 , 18 ] Several photodetectors of this geometry have been reported with sensitivity at infrared wavelengths ( λ > 700 nm). The structure described by Konstantatos et al , consisting of a single spin-coated fi lm of PbS QDs deposited over interdigitated gold electrodes, has been of particular interest due to its high reported specifi c detectivity ( D * ) of ∼ 10 13 Jones, which is comparable to that of state-of-the-art epitaxiallygrown InGaAs photodetectors. A critical problem with this device structure, however, is that it exhibits a very slow temporal response ( f 3dB < 20 Hz) attributed to long-lived QD surface traps.