Search results for "doping"

Cation Diffusion and Segregation at the Interface between Samarium-Doped Ceria and LSCF or LSFCu Cathodes Investigated with X-ray Microspectroscopy

2017

The chemical compatibility between electrolytes and electrodes is an extremely important aspect governing the overall impedance of solid-oxide cells. Because these devices work at elevated temperatures, they are especially prone to cation interdiffusion between the cell components, possibly resulting in secondary insulating phases. In this work, we applied X-ray microspectroscopy to study the interface between a samarium-doped ceria (SDC) electrolyte and lanthanum ferrite cathodes (La0.4Sr0.6Fe0.8Cu0.2O3(LSFCu); La0.9Sr0.1Fe0.85Co0.15O3(LSCF)), at a submicrometric level. This technique allows to combine the information about the diffusion profiles of cations on the scale of several micromet…

Efficient Monolithic Perovskite/Perovskite Tandem Solar Cells

2016

Thin-film solar cells suffer from various types of recombination, of which leakage current usually dominates at lower voltages. Herein, we demonstrate first a three-order reduction of the shunt loss mechanism in planar methylammonium lead iodide perovskite solar cells by replacing the commonly used hole transport layer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with a better hole-selective polyarylamine. As a result, these cells exhibit superior operation under reduced light conditions, which we demonstrate for the extreme case of moonlight irradiance, at which open-circuit voltages of 530 mV can still be obtained. By the shunt removal we also observe the VOC to dro…

HAPPY Dyes as Light Amplification Media in Thin Films

2021

A series of 1Hamorphous tri-phenyl pyridine (HAPPY) dyes have been synthesized from luminescent triphenyl-group-containing 2-methyl-6-styryl-substituted-4H-pyran-4-ylidene derivatives in reactions with benzylamine and investigated for suitability as solution-processable light-emitting medium components in thin films for amplified spontaneous emission (ASE). Conversion of a 4H-pyrane ring into a 1H-pyridine fragment enables aggregation-induced emission enhancement (AIEE) behavior in the target products and slightly increases thermal stability, glass transition temperatures, and ASE efficiency with PLQY up to 15% and ASE thresholds as low as 46 μJ/cm2 in neat spin-cast films, although thermal…

Amplified spontaneous emission of glass forming DCM derivatives in PMMA films

2014

4-(dicyanomethylene)-2-methyl- 6-(p-dimethylaminostyryl)-4H-pyran ( DCM ) is well known red laser dye which can be used also in solid state organic lasers. The lowest threshold value of amplified spontaneous emission was achieved by doping 2wt% of DCM molecule in tris-(8-hydroxy quinoline) aluminium (Alq

Hybrid LEDs based on ZnO nanowire structures

2017

Abstract This paper summarized the research, development, and state of the art of hybrid ZnO nanowire LEDs, in which electroluminescence is generated at the junction between n-type doped ZnO nanowire structures and specific p-type doped polymers (in particular PEDOT, PEDOT:PSS, or PFO). Different device architectures will be reviewed and discussed with a particular emphasis on the electronic transport through the hybrid structures and the microscopic processes of light emission. Finally, a gas-phase deposition technique for conductive polymers will be presented which might help improve the performance of hybrid ZnO nanowire LEDs in the future.

Enhanced thermoelectric performance of PEDOT with different counter-ions optimized by chemical reduction

2014

This work reports on the synthesis of the intrinsically conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with several counter-ions, ClO4, PF6 and bis(trifluoromethylsulfonyl)imide (BTFMSI), by electro-polymerization and its thermoelectric properties. We show that, depending on the counter-ion size, the thermoelectric efficiency of PEDOT can be increased up to two orders of magnitude. A further chemical reduction with hydrazine optimizes the power factor (PF). By changing the counter-ions, we were able to increase the electrical conductivity (σ) of PEDOT by a factor of three, while the Seebeck coefficient remains at the same order of magnitude in the three polymers. The best…

Modified Donnan phenomena in polyaniline with poly(vinyl sulphonate) chains

1993

We develop a physical model, based on the modified Donnan phenomena ideas introduced previously by the authors, to describe the acid doping of the conducting polymer polyaniline. The theory is motivated by the experimental work of Asturias et al. [Ber. Bunsenges. Phys. Chem. 95, 1381 (1991)]. Good agreement between theory and experiment is found.

Deep Levels in Silicon Doped n-Indium Selenide

1992

Growth and characterization of GdxHg1−xSe crystals

2008

Abstract The growth of GdxHg1−xSe crystals by the vertical Bridgman method was studied in the composition range 0⩽x⩽0.1. The structural and electronic properties of GdxHg1−xSe crystals were investigated as a function of composition. It was found that an increase in gadolinium content up to x=0.01 results in a decrease of structural defects and an increase in electron mobility up to the maximum value of μ77≈2.8×105 cm2/V s. Structural defects start to increase at x>0.01, and the formation of Gd2Se3 amorphous phase takes place at x>0.03. On the base of the electron-spin resonance investigation, it was shown that the Gd incorporates into the HgSe host in Gd3+ charge state at the concentration …

Polarization holographic recording in Disperse Red1 doped polyurethane polymer film

2011

In this report holographic recording of polarisation and surface relief gratings in Disperse Red 1 (DR1) doped polyurethane polymer films was studied. In this material DR1 is chemically bounded to polyurethane polymer main chain. Polarization holographic recording was performed by two orthogonal circularly polarized 532 nm laser beams. Photoinduced birefringence is a precondition for polarization holograms recording, therefore a detailed study of a photoinduced birefringence and changes of optical properties was performed. The lasers with wavelengths of 375nm, 448nm, 532 nm and 632.8 nm were used as pumping beam for sample excitation. The photoinduced birefringence Δn was measured at 532 nm…