Shi-Jian Su

Realizing solution‐processable deep‐red circularly polarized organic light‐emitting diodes (CP‐OLEDs) with both intense CP and high color purity remains a formidable challenge. Herein, we report the first solution‐processed narrowband deep‐red circularly polarized hyperfluorescence OLEDs based on a helically chiral boron‐dipyrromethene emitter. Intramolecular boron–oxygen (B–O) covalent fusion simultaneously regulates molecular conjugation and conformational rigidity, thereby suppressing excited‐state structural relaxation and vibronic coupling while preserving efficient deep‐red emission. As a result, BDP‐BO exhibits deep‐red emission at 654 nm with a high photoluminescence quantum yield of 71% and an ultranarrow emission bandwidth of 34 nm (0.10 eV). The corresponding P ‐ and M ‐enantiomers display excellent chiroptical activity, with a luminescence dissymmetry factor (| g _lum |) up to 3.54 × 10 ⁻³ and a circularly polarized luminescence brightness ( B _CPL ) of 49 M ⁻¹ cm ⁻¹ . Exploiting these merits, the M ‐ BDP‐BO ‐based device delivers deep‐red electroluminescence (EL) within the National Television System Committee color gamut, a maximum external quantum efficiency of 2.6%, and a large EL dissymmetry factor (| g _EL |) of 5.49 × 10 ⁻³ . This work establishes B–O covalent fusion as an effective strategy for simultaneously regulating molecular conjugation and conformational rigidity, providing a versatile platform for high‐performance solution‐processed deep‐red CP‐OLEDs.

Realizing solution‐processable deep‐red circularly polarized organic light‐emitting diodes (CP‐OLEDs) with both intense CP and high color purity remains a formidable challenge. Herein, we report the first solution‐processed narrowband deep‐red circularly polarized hyperfluorescence OLEDs based on a helically chiral boron‐dipyrromethene emitter. Intramolecular boron–oxygen (B–O) covalent fusion simultaneously regulates molecular conjugation and conformational rigidity, thereby suppressing excited‐state structural relaxation and vibronic coupling while preserving efficient deep‐red emission. As a result, BDP‐BO exhibits deep‐red emission at 654 nm with a high photoluminescence quantum yield of 71% and an ultranarrow emission bandwidth of 34 nm (0.10 eV). The corresponding P ‐ and M ‐enantiomers display excellent chiroptical activity, with a luminescence dissymmetry factor (| g _lum |) up to 3.54 × 10 ⁻³ and a circularly polarized luminescence brightness ( B _CPL ) of 49 M ⁻¹ cm ⁻¹ . Exploiting these merits, the M ‐ BDP‐BO ‐based device delivers deep‐red electroluminescence (EL) within the National Television System Committee color gamut, a maximum external quantum efficiency of 2.6%, and a large EL dissymmetry factor (| g _EL |) of 5.49 × 10 ⁻³ . This work establishes B–O covalent fusion as an effective strategy for simultaneously regulating molecular conjugation and conformational rigidity, providing a versatile platform for high‐performance solution‐processed deep‐red CP‐OLEDs.

Controlling conformation distributions is the key to manipulate material properties of multi-conformal molecules. Distinct from previous strategy with direct change or impact on the flexible groups, we tune the conformation distribution through changing peripheral groups to influence their intermolecular interactions. Two blue violet TADF emitters, namely tert -butyl substituted 5-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)−10,10-diphenyl-5,10-dihydrodibenzo[b,e][1,4]azagermine (TDBA-PAG) and cumenyl substituted 5-(2,12-bis(2-phenylpropan-2-yl)−5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-7-yl)−10,10-diphenyl-5,10-dihydrodibenzo[b,e][1,4]azagermine (TPDBA-PAG) were designed and synthesized. With the same germanium-integrated donor, the two compounds show similar emission properties in solution with calculated conformation dominantly of their quasi-axial (QA) forms (> 97%). However, TPDBA-PAG presents a lower QA ratio compared with TDBA-PAG, which endows the former with more pronounced TADF emission, higher emission efficiency and reduced concentration quenching phenomena in solid state. As a result, TPDBA-PAG performed as one of the best non-doped and doped violet-blue emitters and successfully sensitized MesB-DIDOBNA-N to achieve record high EQE _max of 24.7% at 406 nm, making significant progress in NUV OLEDs.

Developing highly efficient long‐wavelength exciplexes remains a challenge due to the constraints of the energy gap law and severe non‐radiative loss. In this study, we report a rigid nitrogen‐rich donor, 3N, featuring the first fused framework constructed from two anti‐aromatic phenazine units. This unique architecture ensures 3N has good planarity and an exceptionally shallow highest occupied molecular orbital (HOMO) energy level of −4.88 eV. Meanwhile, the effective suppression of structural relaxation by its rigid scaffold contributes to a narrow emission at 456 nm. By pairing 3N with planar boron‐containing acceptors through strong intermolecular interactions, highly efficient exciplex emissions ranging from green to orange‐red were successfully achieved. Two representative exciplex systems reached outstanding photoluminescence quantum yields of 92% at 557 nm and 78% at 604 nm, respectively. Correspondingly, organic light‐emitting diodes based on these exciplexes delivered maximum external quantum efficiencies of 25.6% at 556 nm and 24.7% at 586 nm, respectively. To the best of our knowledge, these values rank among the highest performance metrics reported for long‐wavelength exciplexes. These results demonstrate that fusing multiple phenazine units could significantly raise the HOMO level and enhances structural rigidity, thereby enabling highly efficient long‐wavelength exciplex electroluminescence.

Developing highly efficient long‐wavelength exciplexes remains a challenge due to the constraints of the energy gap law and severe non‐radiative loss. In this study, we report a rigid nitrogen‐rich donor, 3N, featuring the first fused framework constructed from two anti‐aromatic phenazine units. This unique architecture ensures 3N has good planarity and an exceptionally shallow highest occupied molecular orbital (HOMO) energy level of −4.88 eV. Meanwhile, the effective suppression of structural relaxation by its rigid scaffold contributes to a narrow emission at 456 nm. By pairing 3N with planar boron‐containing acceptors through strong intermolecular interactions, highly efficient exciplex emissions ranging from green to orange‐red were successfully achieved. Two representative exciplex systems reached outstanding photoluminescence quantum yields of 92% at 557 nm and 78% at 604 nm, respectively. Correspondingly, organic light‐emitting diodes based on these exciplexes delivered maximum external quantum efficiencies of 25.6% at 556 nm and 24.7% at 586 nm, respectively. To the best of our knowledge, these values rank among the highest performance metrics reported for long‐wavelength exciplexes. These results demonstrate that fusing multiple phenazine units could significantly raise the HOMO level and enhances structural rigidity, thereby enabling highly efficient long‐wavelength exciplex electroluminescence.

Narrowband deep‐blue emitters featuring a targeted emission peak (465 ± 3 nm) and high reverse intersystem crossing (RISC) rate are highly desirable for ultra‐high‐definition displays. Herein, guided by the para ‐chalcogen‐π‐oxygen alignment strategy, two novel derivatives ( para ‐O‐BN and para ‐S‐BN ) are constructed by peripherally fusing rigid five‐membered chalcogen‐containing (O, S) heterocycles into a classical double‐boron multi‐resonance thermally activated delayed fluorescence (MR‐TADF) skeleton. The extended π‐conjugation and enhanced molecular rigidity yield nearly identical ultra‐narrow deep‐blue emission band at ∼465 nm, with a full width at half maximum below 20 nm in solution. Also, the para ‐arranged chalcogens localize electron density on the central benzene ring inserted between heteroatoms, thereby weakening central boron‐oxygen charge transfer and subtly tuning the HOMO. Importantly, the small singlet‐triplet energy gap (Δ E _ST ) delivers a fast RISC rate ( k _RISC ∼10 ⁵ s ^{− 1} ) and high photoluminescence quantum yield exceeding 90%. Substituting oxygen with sulfur further accelerates RISC process in para ‑S‑BN with negligible spectral shift. OLEDs incorporating para ‑O‑BN / para ‑S‑BN demonstrate maximum external quantum efficiencies ( EQE _max ) of 34.1% and 40.2%, respectively. Notably, sensitizing devices with exciplex host and phosphorescent sensitizer achieve EQE _max of 34.5/35.2% and retain 23.7%/23.8% even at 10 000 cd m ⁻² , with lifetimes of 121.5/244.1 h to 50% of 1000 cd m ⁻² .

Immunotherapy has emerged as a cornerstone of cancer treatment, yet its efficacy is often limited by the immunosuppressive tumor microenvironment, which is marked by low immunogenicity and insufficient cytotoxic T cell infiltration. To address these challenges, we have developed an innovative thermally activated delayed fluorescence (TADF)‐based photosensitizer, termed TA2O. Leveraging its advantageous TADF properties, including a small singlet‐triplet energy gap and prolonged triplet state lifetime, TA2O efficiently generates reactive oxygen species (ROS) upon light irradiation. This process triggers caspase‑1/GSDME‑dependent pyroptosis, leading to the release of tumor‐associated antigens and damage‐associated molecular patterns that stimulate adaptive immunity. Concurrently, the accumulation of cytosolic DNA activates the cGAS‐STING pathway, thereby bolstering innate immune responses. Both in vitro and in vivo studies demonstrate that TA2O effectively eradicates tumor cells, promotes dendritic cell (DC) maturation, facilitates cytotoxic T lymphocyte infiltration, and induces a marked M2‐to‐M1 macrophage polarization, effectively promoting immune infiltration and inflammatory remodeling of the tumor microenvironment. Moreover, a combinatorial strategy integrating TA2O‐mediated photodynamic therapy with anti‐PD‐1 immune checkpoint blockade (ICB) exhibits superior antitumor efficacy compared to either monotherapy. This immuno‐phototherapeutic approach represents a promising advance in precision cancer immunotherapy.

Immunotherapy has emerged as a cornerstone of cancer treatment, yet its efficacy is often limited by the immunosuppressive tumor microenvironment, which is marked by low immunogenicity and insufficient cytotoxic T cell infiltration. To address these challenges, we have developed an innovative thermally activated delayed fluorescence (TADF)‐based photosensitizer, termed TA2O. Leveraging its advantageous TADF properties, including a small singlet‐triplet energy gap and prolonged triplet state lifetime, TA2O efficiently generates reactive oxygen species (ROS) upon light irradiation. This process triggers caspase‑1/GSDME‑dependent pyroptosis, leading to the release of tumor‐associated antigens and damage‐associated molecular patterns that stimulate adaptive immunity. Concurrently, the accumulation of cytosolic DNA activates the cGAS‐STING pathway, thereby bolstering innate immune responses. Both in vitro and in vivo studies demonstrate that TA2O effectively eradicates tumor cells, promotes dendritic cell (DC) maturation, facilitates cytotoxic T lymphocyte infiltration, and induces a marked M2‐to‐M1 macrophage polarization, effectively promoting immune infiltration and inflammatory remodeling of the tumor microenvironment. Moreover, a combinatorial strategy integrating TA2O‐mediated photodynamic therapy with anti‐PD‐1 immune checkpoint blockade (ICB) exhibits superior antitumor efficacy compared to either monotherapy. This immuno‐phototherapeutic approach represents a promising advance in precision cancer immunotherapy.

Narrowband organic light‐emitting diodes (OLEDs) have attracted growing interest, with remarkable progress achieved in the blue/green/red spectral regions. In contrast, realizing narrowband near‐infrared (NIR) OLEDs remains both crucial and challenging. In this work, we present a class of narrowband NIR fluorescent emitters featuring dual boron‐dipyrromethene (BODIPY) cores, reinforced by a hydrogen‐bonding‐locked strategy to achieve spectral purity. The proposed strategy increases molecular rigidity and narrows the full‐width at half‐maximum (FWHM) by suppressing stretching/scissoring vibrations. The proof‐of‐concept emitter αα‐BDP ₂ exhibits narrowband NIR emission centered at 713 nm with a FWHM of only 31 nm (0.076 eV), while ββ‐BDP ₂ achieves an exceptionally high photoluminescence quantum yield (PLQY) of 98% in toluene solution. By employing the developed BODIPY‐derived materials as terminal emitters, solution‐processed narrowband NIR OLEDs have been assembled with external quantum efficiency as high as 2.7% at 713 nm with FWHM of 55 nm. This work, according to the knowledge, represents one of the best instances of solution‐processed narrowband NIR OLEDs based on typical fluorescent emitters.