Bruno Schmaltz

F-AQM , first fluorenyl-flanked para -azaquinodimethane derivative, highlights red-shifted absorption, reduced bandgap, and improved photostability thanks to increased conjugation.

The strategic molecular design of interfacial layers presents a critical pathway to mitigate losses in perovskite photovoltaics. Here, we engineer two carbazole-based polymers with distinct connectivity patterns, 3,6-3,6-Cbz and 3,6-2,7-Cbz, to systematically investigate molecular connectivity-dependent interfacial phenomena in planar n-i-p PSCs. Comprehensive structure-property analyses reveal that the 3,6-2,7-Cbz architecture enables exceptional π-electron delocalization and optimal energy level alignment, simultaneously achieving (i) superior perovskite surface defect passivation and (ii) interfacial recombination suppression. When implemented as an interfacial modifier, the 3,6-2,7-Cbz polymer delivers a champion device efficiency of 24.16% (V_oc = 1.16 V, J_sc = 25.60 mA/cm², FF = 80.86%) with Spiro-OMeTAD as the HTL representing a significant improvement over both the control (22.61%) and 3,6-3,6-Cbz analogue (22.58%). Strikingly, this approach maintains high performance (23.17% PCE) even with undoped carbazole HTLs (Cz-Pyr), demonstrating remarkable versatility. Through correlated XPS and SCLC characterization, we establish clear structure-performance relationships between polymer connectivity and charge transport dynamics. This work provides fundamental insights into molecular topology engineering for advanced interfacial materials in next-generation photovoltaics.

The design and synthesis of sAQM-1, a para-azaquinodimethane-based non-ring fused, narrow gap organic π-conjugated molecule with an undemanding, metal-free synthetic route, is reported.

Modifying the polymer backbone through N⋯S non‐covalent interactions is an effective approach to enhance the properties of organic semiconducting polymers. Following this strategy, we designed and synthesized two new quinoidal polymers based on asymmetric and symmetric thiazole‐flanked para ‐azaquinodimethane ( p ‐AQM), named PAQM‐TTTz and PAQM‐TzTTz . To assess the impact of the thiazole unit, we also synthesized a reference polymer, PAQM‐TTT , and compared its optoelectronic, thermal, and polymer backbone planarity properties with those of PAQM‐TTTz and PAQM‐TzTTz . Both PAQM‐TTTz and PAQM‐TzTTz exhibited dual‐band absorption in solution, indicating pre‐aggregation due to enhanced intermolecular interactions. Both polymers exhibited a low band gap. Density functional theory (DFT) studies revealed that while the thiazole unit does not alter the bond lengths of adjacent thiophenes, but it reduces torsional disorder by forming N⋯S non‐covalent interactions with adjacent thiophenes in PAQM‐TTTz and PAQM‐TzTTz . However, due to the reduced electron richness of the conjugated backbone, a lower charge carrier mobility was observed in field‐effect transistors for PAQM‐TTTz and PAQM‐TzTTz in comparison to PAQM‐TTT . Our results highlighted the interest of non‐covalent interactions in quinoidal polymers and present an alternative design strategy to control the properties of p ‐AQM‐based quinoidal semiconducting polymers.

A series of novel conjugated semiconducting polymers based on the unsubstituted thiazolo[5,4‐ d ]thiazole (TzTz) unit is synthesized using atom‐economic and environmentally friendly direct (hetero)arylation polymerization (DHAP). The versatility of the proposed polymerization conditions, employing a non‐chlorinated and moderately toxic solvent and cooperative palladium/copper bimetallic catalytic system, is demonstrated through the use of seven comonomers with varying electron‐withdrawing strength: 2,2′‐bithiophene (BT), 6,7‐difluoroquinoxaline (Qx), thieno[3,4‐ c ]pyrrole‐4,6(5H)‐dione (TPD), 5,6‐difluorobenzo[ c ][1,2,5]thiadiazole (BTD), isoindigo (IID), para‐azaquinodimethane (AQM) and 2,5‐dihydropyrrolo[3,4‐c]pyrrole‐1,4‐dione (DPP). The resulting TzTz‐based copolymers exhibit optical bandgaps between 1.5 and 2.0 eV with HOMO/LUMO energy levels spanning from −5.2/−3.3 eV to −5.4/−3.9 eV. They all show satisfactory thermal stability for electronic applications (Td = 300−360 °C). Notably, TzTz‐based copolymers are observed they generally exhibit improved backbone planarity and deeper LUMO levels than their thiophene derivatives. A synthesis tool to finely lower the LUMO levels of next‐generation A‐A’ copolymers in view of increasing the performance and air‐stability of doped organic electronics is believed to be provided by this work.

Understanding the impact of the aluminum zinc oxide (AZO) seed layer thickness on zinc oxide nanowires (ZnO NWs) growth is decisive in attaining high‐quality NWs with higher transparency and without cracking issues when using flexible substrates, especially for optoelectronic applications. Therefore, herein, ZnO NWs have been grown on various thicknesses of AZO films deposited onto flexible substrates (PET, PET/ITO (60 Ω sq⁻¹) and (200 Ω sq⁻¹)) through a simple, low‐temperature hydrothermal growth process. Based on AZO layer thickness, structural, optical, morphological, and topographical properties have been systematically investigated. The results demonstrate that 1) thicker AZO films (≈250 nm) increase the crystallinity of the ZnO NWs than thinner AZO films (≈200 and 100 nm). 2) ZnO NWs on the thicker AZO films with different ITO grades (60 or 200 Ω sq⁻¹) provide an optical bandgap value of 3.24–3.27 eV and offer good transmittance (>80%) in the visible range. 3) The AZO film thickness strongly influences ZnO NWs growth, especially NWs’ average diameter and density. 4) Annealing the samples at 100 °C after NW growth is pointless. Overall, the findings demonstrate efficient tuning of the ZnO NW properties that exhibit promising potentiality for perovskite solar cells, which have also been preliminarily tested.

Although disubstituted imidazolium cation is sterically crowded, hundreds of ionic liquids based on this cation have been reported as electrolytes for energy storage devices. In contrast to disubstituted imidazolium, non-substituted imidazolium is uncrowded sterically and has not yet been investigated as an electrolyte, to the best of our knowledge. Hence, imidazolium hydrogen sulfate [Imi][HSO₄], in mixture with water, was studied as an electrolyte for PANI-based electrode materials. For comparison, pyrrolidinium with hydrogen sulfate or p-toluene sulfonate ([Pyrr][HSO₄] or [Pyrr][PTS]), in mixture with water, were also investigated as alternatives to the conventional electrolyte (i.e., aqueous H₂SO₄) for PANI electrodes. Walden plots of binary mixture ionic liquid–water weight ratios with the optimal ionic conductivity (i.e., [Imi][HSO₄]/water 48/52 wt% (195.1 mS/cm), [Pyrr][HSO₄]/water 41/59 wt% (186.6 mS/cm), and [Pyrr][PTS]/water 48/52 wt% (43.4 mS/cm) along with the electrochemical performances of PANI in these binary mixtures showed that [Pyrr][HSO₄]_aq or [Imi][HSO₄]_aq are convenient electrolytes for PANI/PIL, as opposed to [Pyrr][PTS]_aq. Furthermore, replacing the conventional aqueous electrolyte H₂SO₄ with [Imi][HSO₄] _aq increased the specific capacitance of PANI/PIL from 249.8 to 268.5 F/g at 15 mV/s. Moreover, PANI/PIL electrodes displayed a quasi-ideal capacitive behavior in [Imi][HSO₄]_aq (the correction factor of CPE₄ was 0.99). This primary study has shown that non-substituted imidazolium as an electrolyte could enhance the electrochemical performances of PANI electrodes and could be a good alternative to the conventional electrolyte.

Quinoid single molecules are regarded as promising materials for electronic applications due to their tunable chemical structure-driven properties. A series of three single bio-inspired quinoid materials containing para-azaquinodimethane (p-AQM) moiety were designed, synthesized and characterized. AQM1, AQM2 and AQM3, prepared using aldehydes derived from almonds, corncobs and cinnamon, respectively, were studied as promising quinoid materials for optoelectronic applications. The significance of facile synthetic procedures is highlighted through a straightforward two-step synthesis, using Knoevenagel condensation. The synthesized molecules showed molar extinction coefficients of 22,000, 32,000 and 61,000 L mol⁻¹ cm⁻¹, respectively, for AQM1, AQM2 and AQM3. The HOMO-LUMO energy gaps were calculated experimentally, theoretically showing the same trends: AQM3 < AQM2 < AQM1. The role of the aryl substituent was studied and showed an impact on the electronic properties. DFT calculations show planar structures with quinoidal bond length alternation, in agreement with the experimental results. Finally, these bio-based materials showed high thermal stabilities between 290 °C and 340 °C and a glassy behavior after the first heating–cooling scan. These results highlight these bio-based single molecules as potential candidates for electronic or biomedical applications.

Strong p-type doping of alternated donor–acceptor copolymers induces p → n polarity switching upon progressive band filling, the change of polarity coinciding with the maximum of charge conductivity. This study uncovers the role of the dopant's location in the semi-crystalline structure of the conjugated polymer on the mechanism of polarity switching in highly aligned polymer films of two alternated donor–acceptor copolymers. Using a combination of transmission electron microscopy and polarized UV-vis-NIR spectroscopy, the polarity switching is only observed when the dopants are present in both the crystalline and the amorphous domains of the polymer. This is observed for dopants such as FeCl₃. In strong contrast, the dopant magic blue is not able to induce polarity switching because the dopants are not intercalated into the crystals but only in the amorphous phase of the polymer semiconductors. The precise location of dopants in the semi-crystalline structure of a polymer semiconductor is therefore a handle to induce or not the polarity switch and to tune the thermoelectric and charge transport properties of doped polymer semiconductors.