Models of semiconductor quantum dots blinking based on spectral diffusion -=SUP=-*-=/SUP=-

Three models of single colloidal quantum dot emission fluctuations (blinking) based on spectral diffusion were considered analytically and numerically. It was shown that the only one of them, namely the Frantsuzov and Marcus model reproduces the key properties of the phenomenon. The other two models, the Diffusion-Controlled Electron Transfer (DCET) model and the Extended DCET model predict that after an initial blinking period, most of the QDs should become permanently bright or permanently dark which is significantly different from the experimentally observed behavior.

Charge - Transfer Complexes of Metal Dithiolenes XXIV: Ion Pairs of the Tetrakis(dimethylamino)ethene Dication with Dithiolene Metalate Dianions

The dication of tetrakis(dimethylamino)ethene (TDAE2+) forms ion pair complexes with [M(mnt)2]2-, mnt2-= maleonitrile-2,3-dithiolate, M(II) = Ni, Pd, Pt, and Zn. According to X-ray analysis the structure of {TDAE2+[Pt(mnt)2]2- } consists of a chain-like arrangement of planar dianions and twisted (71°) dications. Shortest interionic contacts are 11 pm longer than the corresponding van der Waals radii. In the UV-VIS diffuse reflectance spectra of the complexes with a d8 central metal there is no unambiguous evidence for the presence of an ion pair CT band. This band is observed, however, at 450 nm when the d10 metal Zn(II) is present. Application of the Hush-Marcus model affords a reorganization energy of 110 kJ / mol for electron transfer from [Zn(mnt)2]2- to TDAE2+. This value is 40 kJ / mol higher than the one reported for the analogous complex wherein TDAE2+ is replaced by a 2,2′-bipyridinium acceptor of similar reduction potential