Detection of Single Charge Trapping Defects in Semiconductor Particles by Evaluating Photon Antibunching in Delayed Photoluminescence.

Time-resolved analysis of photon cross-correlation function (τ) is applied to photoluminescence (PL) of individual submicrometer size MAPbI perovskite crystals. Surprisingly, an antibunching effect in the long-living tail of PL is observed, while the prompt PL obeys the photon statistics typical for a classical emitter. We propose that antibunched photons from the PL decay tail originate from radiative recombination of detrapped charge carriers which were initially captured by a very limited number (down to one) of shallow defect states.

Contribution of electron-phonon coupling to the luminescence spectra of single colloidal quantum dots.

Luminescence spectroscopy experiments were realized for single colloidal quantum dots CdSe/ZnS in a broad temperature range above room temperature in a nitrogen atmosphere. Broadening and shifts of spectra due to the temperature change as well as due to spectral diffusion processes were detected and analyzed. A linear correlation between the positions of maxima and the squared linewidths of the spectra was found.

Fluorescence microscopy and spectroscopy of subsurface layer dynamics of polymers with nanometer resolution in the axial direction.

We studied the dynamics in ultrathin subsurface layers of an amorphous polymer by the spectra of single fluorescent molecules embedded into the layer by vapor deposition and subsequent controlled diffusion to the desired depth in ≈0.5 nm steps. The spectral trails of single molecules were recorded at 4.

Low temperature spectral dynamics of single molecules in ultrathin polymer films.

We studied the spectral dynamics of single fluorescent dye molecules embedded in ultrathin films (5 - 100 nm) of the amorphous polymer polyisobutylene at cryogenic temperatures and its variation with film thickness. Noticeable portion of molecules in the ensemble shows a behavior which is inconsistent with the standard tunneling model: Their spectral lines are subject to irreversible spectral jumps, continuous shifting, and abrupt chaotic changes of the linewidth or jumping rate. In films thinner than 100 nm, the occurrence of "non-standard" spectral behavior increases with decreasing sample thickness at fixed excitation intensity.

Low-temperature dynamics in amorphous polymers and low-molecular-weight glasses--what is the difference?

Numerous experiments have shown that the low-temperature dynamics of a wide variety of disordered solids is qualitatively universal. However, most of these results were obtained with ensemble-averaging techniques which hide the local parameters of the dynamic processes. We used single-molecule (SM) spectroscopy for direct observation of the dynamic processes in disordered solids with different internal structure and chemical composition.

Impurity spectroscopy at its ultimate limit: relation between bulk spectrum, inhomogeneous broadening, and local disorder by spectroscopy of (nearly) all individual dopant molecules in solids.

We present a technique for the measurement of the low-temperature fluorescence excitation spectra and imaging of a substantial fraction of all single chromophore molecules (hundreds of thousands and even more) embedded in solid bulk samples as nanometre-sized probes. An important feature of our experimental studies is that the full information about the lateral coordinates and spectral parameters of all individual molecules is stored for detailed analysis. This method enables us to study a bulk sample in a broad spectral region with ultimate sensitivity, combining excellent statistical accuracy and the capability of detecting rare events.

Ortho-dichlorobenzene doped with terrylene--a highly photo-stable single-molecule system promising for photonics applications.

The study of a new dye-matrix system-quickly frozen ortho-dichlorobenzene weakly doped with terrylene--via single-molecule (SM) spectroscopy is presented. The spectral and photo-physical properties, dynamics, and temperature broadening of SM spectra at low temperatures are discussed. The data reveal a broad inhomogeneous distribution, which indicates a high degree of matrix inhomogeneities, but at the same time, huge fluorescence emission rates and extraordinary SM spectral and photochemical stability with almost complete absence of blinking and bleaching.

Dispersion of the local parameters of quasilocalized low-frequency vibrational modes in a low-temperature glass: direct observation via single-molecule spectroscopy.

Spectra of single tetra-tert-butylterrylene chromophore molecules embedded in an amorphous polyisobutylene matrix as microprobes were recorded. The individual temperature dependences of the spectral linewidths for the same single molecules (SMs) in a broad temperature interval (1.6 < T < 40 K) have been measured.