Crystal structure and Hirshfeld surface analysis of 2-bromo-ethyl-ammonium bromide - a possible side product upon synthesis of hybrid perovskites.

This study presents the synthesis, characterization and Hirshfeld surface analysis of a small organic ammonium salt, CHBrN·Br. Small cations like the one in the title compound are considered promising components of hybrid perovskites, crucial for optoelectronic and photovoltaic applications. While the incorporation of this organic cation into various hybrid perovskite structures has been explored, its halide salt counterpart remains largely uninvestigated.

Phase Transitions, Dielectric Response, and Nonlinear Optical Properties of Aziridinium Lead Halide Perovskites.

Hybrid organic-inorganic lead halide perovskites are promising candidates for next-generation solar cells, light-emitting diodes, photodetectors, and lasers. The structural, dynamic, and phase-transition properties play a key role in the performance of these materials. In this work, we use a multitechnique experimental (thermal, X-ray diffraction, Raman scattering, dielectric, nonlinear optical) and theoretical (machine-learning force field) approach to map the phase diagrams and obtain information on molecular dynamics and mechanism of the structural phase transitions in novel 3D AZRPbX perovskites (AZR = aziridinium; X = Cl, Br, I).

Effect of Aging and PCBM Content on Bulk Heterojunction Organic Solar Cells Studied by Intensity Modulated Photocurrent Spectroscopy.

A series of encapsulated and nonencapsulated bulk heterojunction photovoltaic devices containing poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C butyric acid methyl ester (PCBM) with different P3HT:PCBM ratios were investigated using traditional steady-state as well as non-steady-state intensity modulated photocurrent spectroscopy (IMPS) techniques. The steady state J-V measurements showed that PCBM content did not have a significant effect on the efficiency for freshly prepared devices, whereas aged nonencapsulated devices exhibited a strong dependence on PCBM content. IMPS measurements showed a significant contribution of interfacial nongeminate recombination in nonencapsulated devices, which increased with decreasing PCBM content in the photoactive layer and cell aging.

Directed differentiation of embryonic P19 cells and neural stem cells into neural lineage on conducting PEDOT-PEG and ITO glass substrates.

Differentiation of pluripotent and lineage restricted stem cells such as neural stem cells (NSCs) was studied on conducting substrates of various nature without perturbation of the genome with exogenous genetic material or chemical stimuli. Primary mouse adult neural stem cells (NSCs) and P19 pluripotent embryonal (P19 EC) carcinoma cells were used. Expression levels of neuronal markers β-III-tubulin and neurofilament were evaluated by immunochemistry and flow cytometry.

The role of redox environment in neurogenic development.

The dynamic changes of cellular redox elements during neurogenesis allow the control of specific programs for selective lineage progression. There are many redox couples that influence the cellular redox state. The shift from a reduced to an oxidized state and vice versa may act as a cellular switch mechanism of stem cell mode of action from proliferation to differentiation.

Photocurrent generation in carbon nitride and carbon nitride/conjugated polymer composites.

The semiconductor and photovoltaic properties of carbon nitride (CNx) thin films prepared using a reactive magnetron cathodic sputtering technique were investigated both individually and as composites with an organic conjugated polymer, poly(2,2'-bithiophene) (PBT). The CNx films showed an increasing thickness as the deposition power and/or nitrogen content in the gas mixture increase. At low nitrogen content and low deposition power (25-50 W), the film structure was dominated by the abundance of the graphitic sp(2) regions, whereas at higher nitrogen contents and magnetron power CNx films started to demonstrate semiconductor properties, as evidenced by the occurrence of photoconductivity and the development of a space charge region.

p53-mediated regulation of neuronal differentiation via regulation of dual oxidase maturation factor 1.

The p53 transcription factor is involved in cell cycle, apoptosis and differentiation. However, the mechanism of p53 mediated differentiation is not fully understood. Here, we show that recently discovered dual oxidase maturation factor 1 (DUOXA1), which was implicated in neuronal differentiation, is regulated by p53 and may be an important factor in neuronal differentiation.

Mechanism of recombination losses in bulk heterojunction P3HT:PCBM solar cells studied using intensity modulated photocurrent spectroscopy.

Intensity modulated photocurrent (IMPS) and photovoltage (IMVS) spectroscopies were used to study the mechanism of photoprocesses in P3HT:PCBM bulk heterojunction organic solar cells at various light intensities. The use of the frequency domain techniques allowed us to separate the bulk and interfacial processes and gain a valuable insight into the mechanism of losses in these devices. The results provide direct evidence that interfacial nongeminate recombination is one of the dominant loss and aging mechanisms in bulk heterojunction organic solar cells.

Electrochemical and photovoltaic properties of electropolymerized poly(thienylsilole)s.

Electrochemical and photoelectrochemical properties were studied of a series of donor-acceptor materials based on polythiophene modified with silole moieties. The materials were prepared by electrochemical anodic polymerization of 2,5-bis([2,2'-bithiophen]-5-yl)-1,1-dimethyl-3,4-diphenylsilole and 2,5-bis([2,2'-terthiophen]-5-yl)-1,1-dimethyl-3,4-diphenylsilole, as well as copolymerization of these monomers with 2,2'-bithiophene. Photocurrent measurements showed that introduction of silole resulted in a considerable enhancement of the photovoltaic properties of silole-containing materials and especially the fill factor.

On the origin of mesoscopic inhomogeneity of conducting polymers.

The mesoscopic inhomogeneity of conducting polymer films obtained by electropolymerization and spin-coating was studied using Kelvin probe force microscopy (KFM) and current-sensing atomic-force microscopy (CS-AFM). A well-pronounced correlation was established between the polymer morphology, on the one hand, and its local work function (which is related to the polymer oxidation degree) as well as polymer conductivity, on the other. The most conducting regions were associated with the tops of the polymer grains and showed Ohmic behavior.

Photoelectrochemistry of conducting polymers modified with electron-acceptor moieties.

The photoelectrochemical behavior of two polymers of the polythiophene series containing electron-acceptor groups in the main chain was studied and compared to that of the nonmodified polymer, poly(2,2'-bithiophene), PBT. The acceptor groups were 2,2'-bipyridine and biphenyl, which are electron-deficient as compared to the bithiophene unit. All three polymers demonstrated a pronounced photovoltaic effect, which for PBT was consistent with data reported earlier.