Photophysical characteristics and photosensitizing abilities of thieno[3,2-b]thiophene-Based photosensitizers for photovoltaic and photocatalytic applications

High-Performance Photocatalytic Hydrogen Generation Using Robust Dianchoring Photosensitizers

A novel series of donor-donor-π-acceptor (D-D-π-A) 9,9'-dihexylfluorene-based dianchoring organic dyes, each featuring distinct bridging electron-donating moieties, have been synthesized and characterized. Their performances in photocatalytic hydrogen evolution (PHE) were evaluated, taking into account of their photophysical and electrochemical attributes. Remarkably, (Z)-3-(5-(4-((4-(5-((E)-2-carboxy-2-cyanovinyl)thiophen-2-yl)phenyl)(9,9-dihexyl-9H-fluoren-2-yl)amino)phenyl)thiophen-2-yl)-2-cyanoacrylic acid achieved an active and robust H2 generation system with a turnover number (TON) of up to 17 400 in 126 h, with a production of 1090 μmol (26.3 mL) of hydrogen. The initial turnover frequency (TOFi), initial activity (activityi), and initial apparent quantum yield (AQYi) were 808 h-1, 505 mmol g-1 h-1, and 8.65%, respectively, under visible light irradiation in water. This photosensitizer is considered one of the most effective and durable systems for photocatalytic hydrogen production that attached to molecular Pt-TiO2, as stated out in the literature using organic dyes under visible light, when compared the TOF and TON values. The experimental results demonstrated that the dianchoring dyes with bridging units could significantly enhance PHE performance, maintaining justifiable durability over prolonged irradiation.

Effect of Thiophene-Hydrazinyl-Thiazole derivative as an efficient dye sensitizer and performance enhancer of TiO2 toward rhodamine B photodegradation

Visible-light-driven photocatalysis is an eco-friendly technology for wastewater treatment, where TiO2-based photocatalysts displayed outstanding performance in this regard. Dye sensitization is a promising approach for overcoming the common drawbacks of TiO2via improving its photocatalytic performance and extending its activity to visible light. Herein, we demonstrate the synthesis of the Thiophene-Hydrazinyl-Thiazole (THT) derivative as a novel organic dye sensitizer to be employed as a visible-light antenna for TiO2 nanoparticles. The physicochemical characteristics of the as-synthesized TiO2-based nanoparticles are examined by different techniques, which revealed the successful fabrication of the proposed THT-TiO2 heterojunction. The incorporation of THT molecules on the TiO2 surface led to slight disorders and deformation in the crystal lattice of TiO2, a remarkable improvement of its absorption in the visible light as a perfect visible-light antenna in the whole visible region, and significant enhancement in the charge transfer. Rhodamine B (RhB) is used as an organic dye model to assess the photocatalytic efficiency of the as-fabricated THT-TiO2 photocatalyst which achieved almost complete degradation (>95% in 150 min) with an observed rate constant (kobs) of 0.0164 min-1; total organic carbon (TOC) measurements suggested ∼75% mineralization. THT-TiO2 achieved 2.1-fold enhancement in photodegradation% and 4.1-fold enhancement in kobs compared to the bare TiO2. THT showed good activity under visible-light irradiation (RhB degradation% was >66% in 150 min and kobs = 0.0085 min-1). The influence of the initial pH of the solution was investigated and pH 4 was the optimum pH value for suitable interaction between RhB and the surface of THT-TiO2. Radical quenching experiments were conducted to assess the crucial reactive species where the ∙OH and O2.- were the most reactive species. THT-TiO2 showed promising stability over three successive cycles. Finally, the improvement mechanism of the photocatalytic activity of THT-TiO2 was attributed to the electron injection from the excited THT (the dye sensitizer) to TiO2 and enhanced charge separation.

Enhanced Hole Mobility of p-Type Materials by Molecular Engineering for Efficient Perovskite Solar Cells

Star-shaped triazatruxene derivative hole-transporting materials (HTMs), namely, 3,8,13-tris(4-(8a,9a-dihydro-9H-carbazol-9-yl)phenyl)-5,10,15-trihexyl-10,15-dihydro-5H-diindolo[3,2-a:3',2'-c]carbazole (TAT-TY1) and 3,8,13-tris(4-(8a,9a-dihydro-9H-carbazol-9-yl)phenyl)-5,10,15-trihexyl-10,15-dihydro-5H-diindolo[3,2-a:3',2'-c]carbazole (TAT-TY2), containing electron-rich triazatruxene cores and donor carbazole moieties, were synthesized and successfully used in triple-cation perovskite solar cells. All the HTMs were obtained from relatively inexpensive precursor materials using well-known synthesis procedures and uncomplicated purification steps. All the HTMs, including the 5,10,15-trihexyl-10,15-dihydro-5H-diindolo[3,2-a:3',2'-c]carbazole (TAT-H) main core, had suitable highest occupied molecular orbitals (HOMOs) for perovskite (TAT-H: -5.15 eV, TAT-TY1: -5.17 eV, and TAT-TY2: -5.2 eV). Steady-state and time-resolved photoluminescence results revealed that hole transport from the valence band of the perovskite into the HOMO of the new triazatruxene derivatives was more efficient than with TAT-H. Furthermore, the substitution of n-hexylcarbazole and 9-phenylcarbazole in triazatruxene altered the crystalline nature of the main core, resulting in a smooth and pinhole-free thin-film morphology. As a result, the hole mobilities of TAT-TY1 and TAT-TY2 were measured to be one order of magnitude higher than that of TAT-H. Finally, TAT-TY1 and TAT-TY2 achieved power conversion efficiencies of up to 17.5 and 16.3%, respectively, compared to the reference Spiro-OMeTAD. These results demonstrate that the new star-shaped triazatruxene derivative HTMs can be synthesized without using complicated synthesis strategies by controlling the intrinsic morphology of the TAT-H main core.