Opto-electrical and density functional theory analysis of poly(2,7-carbazole-alt-thieno[3,4-c]pyrrole-4,6-dione) and photovoltaic behaviors of bulk heterojunction structure

Capturing Mobile Lithium Ions in a Molecular Hole Transporter Enhances the Thermal Stability of Perovskite Solar Cells

A thermally stable perovskite solar cell (PSC) based on a new molecular hole transporter (MHT) of 1,3-bis(5-(4-(bis(4-methoxyphenyl) amino)phenyl)thieno[3,2-b]thiophen-2-yl)-5-octyl-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (coded HL38) is reported. Hole mobility of 1.36 × 10^-3 cm² V^-1 s^-1 and glass transition temperature of 92.2 °C are determined for the HL38 doped with lithium bis(trifluoromethanesulfonyl)imide and 4-tert-butylpyridine as additives. Interface engineering with 2-(2-aminoethyl)thiophene hydroiodide (2-TEAI) between the perovskite and the HL38 improves the power conversion efficiency (PCE) from 19.60% (untreated) to 21.98%, and this champion PCE is even higher than that of the additive-containing 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-MeOTAD)-based device (21.15%). Thermal stability testing at 85 °C for over 1000 h shows that the HL38-based PSC retains 85.9% of the initial PCE, while the spiro-MeOTAD-based PSC degrades unrecoverably from 21.1% to 5.8%. Time-of-flight secondary-ion mass spectrometry studies combined with Fourier transform infrared spectroscopy reveal that HL38 shows lower lithium ion diffusivity than spiro-MeOTAD due to a strong complexation of the Li⁺ with HL38, which is responsible for the higher degree of thermal stability. This work delivers an important message that capturing mobile Li⁺ in a hole-transporting layer is critical in designing novel MHTs for improving the thermal stability of PSCs. In addition, it also highlights the impact of interface design on non-conventional MHTs.

Thieno[3,4-c]pyrrole-4,6-dione-based conjugated polymers for organic solar cells

Thieno[3,4-c]pyrrole-4,6-dione (TPD) based conjugated polymers as an electron donor, acceptor and single-component for application in organic solar cells in the past ten years have been intensively reviewed in this Feature Article.

Carbazole-based copolymers via direct arylation polymerization (DArP) for Suzuki-convergent polymer solar cell performance

Direct arylation polymerization (DArP) is used to synthesize a variety of carbazole-based copolymers for evaluation in solar cells.

N-Alkylthienopyrroledione versus benzothiadiazole pulling units in push–pull copolymers used for photovoltaic applications: density functional theory study

Low-band-gap push–pull copolymers are promising donor materials for bulk heterojunction organic solar cells.

Reaction Mechanism for m-Xylene Oxidation in the Claus Process by Sulfur Dioxide

In the Claus process, the presence of aromatic contaminants such benzene, toluene, and xylenes (BTX), in the H2S feed stream has a detrimental effect on catalytic reactors, where BTX form soot particles and clog and deactivate the catalysts. Among BTX, xylenes are proven to be most damaging contaminant for catalysts. BTX oxidation in the Claus furnace, before they enter catalyst beds, provides a solution to this problem. A reaction kinetics study on m-xylene oxidation by SO2, an oxidant present in Claus furnace, is presented. The density functional theory is used to study the formation of m-xylene radicals (3-methylbenzyl, 2,6-dimethylphenyl, 2,4-dimethylphenyl, and 3,5-dimethylphenyl) through H-abstraction and their oxidation by SO2. The mechanism begins with SO2 addition on the radicals through an O-atom rather than the S-atom with the release of 180.0-183.1 kJ/mol of reaction energies. This exothermic reaction involves energy barriers in the range 3.9-5.2 kJ/mol for several m-xylene radicals. Thereafter, O-S bond scission takes place to release SO, and the O-atom remaining on aromatics leads to CO formation. Among four m-xylene radicals, the resonantly stabilized 3-methylbenzyl exhibited the lowest SO2 addition and SO elimination rates. The reaction rate constants are provided to facilitate Claus process simulations to find conditions suitable for BTX oxidation.