Triplet quantum chain process in the photoisomerization of 9-cis retinal as revealed by nanosecond time-resolved infrared spectroscopy

Effect of Cs+ Doping on the Carrier Dynamics of MAPbI3 Perovskite

Organic inorganic perovskite materials have received increasing attention in the optoelectronic field because of their unique properties. The ultrafast dynamics of photogenerated carriers determine photoelectric conversion efficiency, thus, it is feasible to influence the dynamics behavior of photogenerated carriers by regulating A-site cations. This paper mainly used transient absorption spectra (TAS) technology to study the photogenerated carriers relaxation processes of organic-inorganic perovskite CsxMA1-xPbI3 materials at different x values. Three sets of time constants were obtained by global fitting at different values of x. The experimental results showed that the crystal structure of perovskite could be affected by adjusting the Cs+ doping amount, thereby regulating the carrier dynamics. The appropriate amount of A-cation doping not only maintained the organic-inorganic perovskite crystal phase, but also prolonged the photogenerated carrier's lifetime. The 10% Cs+ doping CsxMA1-xPbI3 perovskite has potential for solar cell applications. We hope that our research can provide dynamics support for the development of organic-inorganic perovskite in solar cells.

Femtosecond Transient Absorption Spectra and Dynamics of Carrier Relaxation of Tin Perovskites in the Absence and Presence of Additives

The effects of additives SnF₂ (10%) and EDAI₂ (1%) on the dynamics of carrier relaxation of formamidinium tin triiodide (FASnI₃) perovskite were studied using femtosecond transient absorption spectra (TAS) with excitation at 600 and 870 nm. The TAS were analyzed according to a parallel sequential kinetic model with a global fit through singular-value decomposition. For excitation at 600 nm, two relaxation paths were found: one involved hot and cold carriers in the bulk state undergoing shallow bulk-defect-mediated charge recombination; the other involved trap carriers in the surface state undergoing deep surface-defect-mediated charge recombination. For excitation at 870 nm, only cold carriers were subjected to the bulk-state relaxation channel. Our spectral results indicate significant effects of the additives on retarding charge recombination in both bulk and surface states as well as decreasing the bandgap renormalization energy, the bandwidth of the photobleaching (PB) band, and the Stokes shift between the PB and photoluminescence bands, explaining how the device performance of FASnI₃ solar cells became enhanced in the presence of SnF₂ and EDAI₂.

Complete NMR assignment of retinal and its related compounds

Complete and unambiguous (1)H and (13)C NMR chemical shift assignments for all-trans-retinal, 13-cis-retinal, 11-cis-retinal and 9-cis-retinal (1-4) have been established by means of two-dimensional COSY, HSQC, HMBC and NOESY spectroscopic experiments.

Isolation of the retinal isomers from the isomerization of all-trans-retinal by flash countercurrent chromatography

The isolation of the retinal isomers from all-trans-retinal was performed by flash countercurrent chromatography. In each separation, isomerization reaction solution of 200mg all-trans-retinal could be loaded on a 1200 mL of high-speed countercurrent chromatographic column with 5mm bore, eluted by a mobile phase flow rate of 25 mL/min, resulting in 63 mg of 11-cis-retinal, 24 mg of 13-cis-retinal and 26 mg of 9-cis-retinal with purities more than 95%. n-Hexane-acetonitrile (3:1) was used as the solvent system which possesses the advantages of simplicity, re-use of the solvent and multiple injections. This method could be used to prepare 13-cis-retinal, 11-cis-retinal and 9-cis-retinal for the photoisomerization investigation, such as the effect of 11-cis-retinal in the visual system.