Interplay Between J‐ and H‐Type Coupling in Aggregates of π‐Conjugated Polymers: A Single‐Molecule Perspective

Strong dipole–dipole coupling within and between π‐conjugated segments shifts electronic transitions, and modifies vibronic coupling and excited‐state lifetimes. Since J‐type coupling between monomers along the conjugated‐polymer (CP) chain and H‐type coupling of chromophores between chains of a CP compete, a superposition of the spectral modifications arising from each type of coupling emerges, making the two couplings hard to discern in the ensemble. We introduce a single‐molecule H‐type aggregate of fixed spacing and variable length of up to 10 nm. HJ‐type aggregate formation is visualized intuitively in the scatter of single‐molecule spectra.     

A Unique Blend of 2‐Fluorenyl‐2‐anthracene and 2‐Anthryl‐2‐anthracence Showing White Emission and High Charge Mobility

White‐light‐emitting materials with high mobility are necessary for organic white‐light‐emitting transistors, which can be used for self‐driven OLED displays or OLED lighting. In this study, we combined two materials with similar structures—2‐fluorenyl‐2‐anthracene (FlAnt) with blue emission and 2‐anthryl‐2‐anthracence (2A) with greenish‐yellow emission—to fabricate OLED devices, which showed unusual solid‐state white‐light emission with the CIE coordinates (0.33, 0.34) at 10 V. The similar crystal structures ensured that the OTFTs based on mixed FlAnt and 2A showed high mobility of 1.56 cm² V⁻¹ s⁻¹. This simple method provides new insight into the design of high‐performance white‐emitting transistor materials and structures.     

Topological Transformation of π‐Conjugated Molecules Reduces Resistance to Crystallization

Two electronically delocalized molecules were designed as models to understand how molecular shape impacts the tradeoff between solubility and crystallization tendencies in molecular semiconductors. The more soluble compound TT contains a non‐planar bithiophene central fragment, whereas CT has a planar cyclopentadithiophene unit. Calorimetry studies show that CT can crystallize more easily than TT . However, absorption spectroscopy shows that the initially amorphous TT film can eventually form crystals in which the molecular shape is significantly more planar. Two thermally reversible polymorphs for TT were observed by XRD and grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) measurements. These findings are relevant within the context of designing soft semiconductors that exhibit high solubility and a tendency to provide stable organized structures with desirable electronic properties.     

A One‐Dimensional π–d Conjugated Coordination Polymer for Sodium Storage with Catalytic Activity in Negishi Coupling

π‐d Conjugated coordination polymers (CCPs) have attracted much attention for various applications, although the chemical states and structures of many CCPs are still blurry. Now, a one‐dimensional (1D) π‐d conjugated coordination polymer for high performance sodium‐ion batteries is presented. The chemical states of the obtained coordination polymer are clearly revealed. The electrochemical process undergoes a three‐electron reaction and the structure transforms from C=N double bonds and Ni^II to C?N single bonds and Ni^I, respectively. Our unintentional experiments provided visual confirmation of Ni^I. The existence of Ni^I was further corroborated by its X‐ray absorption near‐edge structure (XANES) and its catalytic activity in Negishi cross‐coupling.     

Effects of Bithiophene Imide Fusion on the Device Performance of Organic Thin‐Film Transistors and All‐Polymer Solar Cells

Two new bithiophene imide (BTI)‐based n‐type polymers were synthesized. f‐BTI2‐FT based on a fused BTI dimer showed a smaller band gap, a lower LUMO, and higher crystallinity than s‐BTI2‐FT containing a BTI dimer connected through a single bond. s‐BTI2‐FT exhibited a remarkable electron mobility of 0.82 cm² V⁻¹ s⁻¹, and f‐BTI2‐FT showed a further improved mobility of 1.13 cm² V⁻¹ s⁻¹ in transistors. When blended with the polymer donor PTB7‐Th, f‐BTI2‐FT‐based all‐polymer solar cells (all‐PSCs) attained a PCE of 6.85 %, the highest value for an all‐PSC not based on naphthalene (or perylene) diimide polymer acceptors. However, s‐BTI2‐FT all‐PSCs showed nearly no photovoltaic effect. The results demonstrate that f‐BTI2‐FT is one of most promising n‐type polymers and that ring fusion offers an effective approach for designing polymers with improved electrical properties.     

A Three‐Dimensionally π‐Conjugated Diradical Molecular Cage

π‐Conjugated molecular cages are very challenging targets in structural organic chemistry, supramolecular chemistry, and materials science. The synthesis and physical characterizations are reported of the first three‐dimensionally π‐conjugated diradical molecular cage PTM‐C, in which two polychlorotriphenylmethyl (PTM) radicals are linked by three bis(3,6‐carbazolyl) bridges. This cage compound was synthesized mainly by intermolecular Yamamoto coupling followed by deprotonation and oxidation. It is stable and its structure was confirmed by X‐ray crystallographic analysis. The two carbon‐centered PTM radicals are weakly coupled through electronic interactions with the carbazole spacers, as revealed by optical, electronic, and magnetic measurements as well as theoretical calculations.     

Synthesis of π‐Conjugated Benzocyclotrimers

Polycyclic aromatic hydrocarbons (PAHs), especially three branchphene benzocyclotrimers represent a series of molecules with intriguing physical and chemical properties. Benzocyclotrimers are also important precursors to construct fullerenes and graphenes. In this article, we review the recent progress in the preparation methods of π‐conjugated benzocyclotrimers. In particular, cyclotrimerization reactions to construct varying shaped and edged benzocyclotrimers are illustrated. Various typical characterization methods for these materials, such as variable‐temperature ¹H‐NMR, single crystal X‐ray analysis, density functional theory (DFT) calculations and atomic force microscope (AFM) measurements are included for discussion.