A high molar extinction coefficient sensitizer for stable dye-sensitized solar cells

An amphiphilic heteroleptic polypyridyl ruthenium complex with a high molar extinction coefficient was synthesized and demonstrated as an efficient, thermostable sensitizer in nanocrystalline dye-sensitized solar cells.     

Asymptotische Entwicklung von Integralen mit zwei Parametern

Ohne Zusammenfassung     

Correlation techniques in dynamic light scattering

The motion of small scatterers in a laser beam results in Doppler shifts of the scattered light. Various homodyne or heterodyne experiments may be used to measure such shifts. The stochastic nature of spatial particle arrangements and of the photon-detection process leads to statistic data processing schemes like temporal correlation or the computation of structure functions. Photon correlation is one of these schemes and has found numerous applications in velocimetry and Brownian motion studies. Topics of current interest are dead-time corrections, the use of photon structure functions, and multiple tau measurements, which access large ranges of time constants in a single run.More recent data processing techniques are recurrence rate correlation for the immediate determination of velocity correlation functions in seeded fluid flows and the measurement of amplitude-weighted phase structure functions, which is able to resolve very small particle displacements otherwise completely obscured by random Brownian motion. Rate correlation found applications in hydrodynamic studies of the route to turbulence, while the major use of phase structure function processing is a very significant increase in the sensitivity of electrophoretic mobility measurements by light scattering.     

Bemerkungen zu einem Gitterpunktsproblem

Ohne Zusammenfassung     

Quantum mechanical repulsion of exciton levels in a disordered quantum well

Spatially resolved photoluminescence spectra of a single quantum well are recorded by near-field spectroscopy. A set of over four hundred spectra displaying sharp emission lines from localized excitons is subject to a statistical analysis of the two-energy autocorrelation function. An accurate comparison with a quantum theory of the exciton center-of-mass motion in a two-dimensional spatially correlated disordered potential reveals clear signatures of quantum mechanical energy level repulsion, giving the spatial and energetic correlations of excitons in disordered quantum systems.     

3‐(tert‐Butyl­oxy­carbonyl­amino)­bicyclo­[1.1.1]­pentane­carboxyl­ic acid at 293 K

In the room‐temperature X‐ray structure of the N‐Boc‐protected derivative of the novel 3‐amino­bi­cyclo[1.1.1]­pentanecarboxyl­ic acid, C₁₁H₁₇NO₄, the interbridgehead distance in the bi­cyclo­[1.1.1]­pentane cage is 1.852 (2) Å. The carboxyl and parts of the blocked amino group are almost in plane with one of the cage triangles. N—H?O and O—H?O hydrogen bonds generate infinite corrugated molecular chains in the crystal lattice.     

Stabilization of Highly Efficient and Stable Phase‐Pure FAPbI3 Perovskite Solar Cells by Molecularly Tailored 2D‐Overlayers

As a result of their attractive optoelectronic properties, metal halide APbI₃ perovskites employing formamidinium (FA⁺) as the A cation are the focus of research. The superior chemical and thermal stability of FA⁺ cations makes α‐FAPbI₃ more suitable for solar‐cell applications than methylammonium lead iodide (MAPbI₃). However, its spontaneous conversion into the yellow non‐perovskite phase (δ‐FAPbI₃) under ambient conditions poses a serious challenge for practical applications. Herein, we report on the stabilization of the desired α‐FAPbI₃ perovskite phase by protecting it with a two‐dimensional (2D) IBA₂FAPb₂I₇ (IBA=iso‐butylammonium overlayer, formed via stepwise annealing. The α‐FAPbI₃/IBA₂FAPb₂I₇ based perovskite solar cell (PSC) reached a high power conversion efficiency (PCE) of close to 23 %. In addition, it showed excellent operational stability, retaining around 85 % of its initial efficiency under severe combined heat and light stress, that is, simultaneous exposure with maximum power tracking to full simulated sunlight at 80 °C over 500 h.