Yi Zhang

Solution‐processed multi‐resonance TADF (MR‐TADF) polymer OLEDs face a persistent design conflict: conjugated backbones broaden and redshift emission via extended π‐delocalization, whereas nonconjugated alternatives preserve narrow spectra but suffer from carrier‐transport imbalance, historically capping external quantum efficiency (EQE) below 20%. Here, we circumvent this dilemma by copolymerizing diamines containing B/N‐fused MR emitters (DBNCzNH ₂ ) and phosphine oxide (P═O) units (TPONH ₂ ) with an aliphatic dianhydride (HBPDA), yielding a set of semi‐aromatic polyimides TPOBN X % ( X = 1, 3, 5, and 10). Our design leverages two synergistic effects: the rigid nonconjugated aliphatic imide ring confines the MR chromophores in its intrinsic short‐range charge‐transfer regime, yielding narrow solution emission (full width at half maximum FWHM = 27–30 nm) and suppressing non‐radiative decay via conformational restriction; simultaneously, the P═O units facilitate electron transport while their σ ‐bond insulation avoids perturbing the MR excited‐state manifold. The optimal TPOBN5% exhibits a minimal singlet‐triplet gap (Δ E _ST ) of 17.5 meV in neat film, favoring reverse intersystem crossing, and an 87% photoluminescence quantum yield in doped film. Solution‐processed OLEDs based on TPOBN5% achieve 25.3% EQE and 33 nm electroluminescence FWHM, representing record performance for nonconjugated MR‐TADF polymers. The synergy of rigid nonconjugated skeletons and polar transport units establishes a generalizable platform to address the efficiency‐color purity trade‐off.

Solution‐processed multi‐resonance TADF (MR‐TADF) polymer OLEDs face a persistent design conflict: conjugated backbones broaden and redshift emission via extended π‐delocalization, whereas nonconjugated alternatives preserve narrow spectra but suffer from carrier‐transport imbalance, historically capping external quantum efficiency (EQE) below 20%. Here, we circumvent this dilemma by copolymerizing diamines containing B/N‐fused MR emitters (DBNCzNH ₂ ) and phosphine oxide (P═O) units (TPONH ₂ ) with an aliphatic dianhydride (HBPDA), yielding a set of semi‐aromatic polyimides TPOBN X % ( X = 1, 3, 5, and 10). Our design leverages two synergistic effects: the rigid nonconjugated aliphatic imide ring confines the MR chromophores in its intrinsic short‐range charge‐transfer regime, yielding narrow solution emission (full width at half maximum FWHM = 27–30 nm) and suppressing non‐radiative decay via conformational restriction; simultaneously, the P═O units facilitate electron transport while their σ ‐bond insulation avoids perturbing the MR excited‐state manifold. The optimal TPOBN5% exhibits a minimal singlet‐triplet gap (Δ E _ST ) of 17.5 meV in neat film, favoring reverse intersystem crossing, and an 87% photoluminescence quantum yield in doped film. Solution‐processed OLEDs based on TPOBN5% achieve 25.3% EQE and 33 nm electroluminescence FWHM, representing record performance for nonconjugated MR‐TADF polymers. The synergy of rigid nonconjugated skeletons and polar transport units establishes a generalizable platform to address the efficiency‐color purity trade‐off.

The advancement of high‐frequency communication and miniaturized electronics necessitates dielectric materials that combine high intrinsic thermal conductivity ( λ ) with low dielectric loss ( D _f ) to mitigate signal delay and thermal accumulation. Conventional strategies, particularly nanocomposite approaches, often struggle to simultaneously achieve high λ and low D _f without compromising processability or mechanical integrity. Herein, a semicrystalline polyimide (TAHQ/TFMB) architecture is initially established by circumventing the amorphous nature of fluorinated systems via rigid‐rod backbone design and programmed thermal processing. Subsequently, minor dynamically exchangeable siloxane segments (≤ 1 mol%) act as molecular disentanglement switches, triggering topological rearrangement that promotes the formation of widely distributed crystal nuclei and enables the subsequent development of large‐scale crystalline domains, ultimately yielding an enhanced crystallinity exceeding 50%. The optimally designed film with merely 0.25 mol% siloxane exhibits an enhanced in‐plane λ of 2.33 W·m ⁻¹ ·K ⁻¹ and an ultralow D _f of 0.00142 at 10 GHz. This synergy facilitates the first realization of a broadband thermoacoustic generator featuring an all‐organic substrate and a flexible hairpin bandpass filter with excellent signal transmission performance. Furthermore, the DBPI‐0.25 film exhibits excellent thermal stability ( T _d5% = 478.3°C), superior moisture resistance (water uptake of 0.41%), and good mechanical flexibility, rendering it highly suitable for advanced microelectronics.

Achieving persistent room‐temperature phosphorescence (RTP) with a time‐dependent afterglow in organic systems is highly attractive for superior optoelectronic applications, yet remains challenging in stability and visible‐light excitation. Herein, we present an efficient strategy of ‘fused framework’ to design a phosphor (TpPTZ) integrated with a triplet‐stabilizing unit and a bending‐vibrational conformation via a shared phenyl ring. It realizes visible‐light excited, robust time‐dependent afterglow when dispersed in polar polymer matrixes. With an ultralow doping content of 0.1 wt.%, the afterglow color switches from yellow to green within seconds, even at an elevated temperature of 343 K. Studies reveal that the dual afterglow originates from two triplet states of the dynamic conformations of TpPTZ. As the bending dihedral angle ( θ _Tp‐ph ) increased, the energy levels of singlet (S ₁ ) and triplet (T ₁ ) excited states intersect at θ _Tp‐ph of 33° and then invert from S ₁ < T ₁ to S ₁ > T ₁ . Thus, a strong yellow afterglow occurs at a small θ _Tp‐ph of ∼30°, and a weak green afterglow arises at θ _Tp‐ph larger than 33°. This work demonstrates a new strategy of ‘fused framework’ for combining new functions into organic persistent RTP molecules, promoting their further diversification of functional properties for optoelectronic and biological applications.

To address the severe structural degradation of silicon anodes induced by substantial volume expansion during cycling, this study designs a high-performance polyimide binder via a synergistic hydrogen-bond network and rigidity-flexibility modulation. The rigid amide-rich framework ensures mechanical robustness and strong interfacial adhesion to silicon particles through hydrogen bonding. Simultaneously, incorporated flexible polyether segments improve structural compliance to buffer volume strain and boost ionic conductivity via enhanced electrolyte wettability. Comprehensive characterization, including in situ temperature-dependent FTIR and XPS analyses, confirms the formation of a resilient internal hydrogen-bond network and strong binder-Si interfacial interactions. This dual strategy endows the optimized PI-5% binder with exceptional properties: ultrahigh adhesion (9.35 N/cm), low electrolyte swelling (5.80%), and enhanced ionic conductivity (0.29 mS·cm⁻¹). These features collectively maintain electrode integrity and stabilize the SEI, leading to outstanding electrochemical performance: an initial Coulombic efficiency of 87.94%, a reversible capacity of 1076.9 mAh·g⁻¹ after 550 cycles at 3.0 A·g⁻¹, and 86.44% capacity retention (2120.7 mAh·g⁻¹) at 1.2 A·g⁻¹, significantly surpassing conventional CMC-based electrodes. This study provides an effective strategy for designing high-performance polyimide binders by elucidating the synergistic interplay between hydrogen-bonding networks and rigidity-flexibility balance, providing theoretical guidance for the development of advanced binders for silicon-based lithium-ion batteries.