Thermally Activated Dual-Room-Temperature Phosphorescence: Triplet Up-Converted Anti-Kasha in Dendrimers Enabled by Rigid Matrix Stabilization

Abstract

Room-temperature phosphorescence (RTP) materials are a significant research field for anti-counterfeiting, bioimaging, and optoelectronic devices, but anti-Kasha RTP still lacks clear molecular design strategies, and conventional rigid polymer matrices fail to break Kasha's rule. To address these issues, this work proposes an acceptor dendronization strategy to synthesize the dendrimer emitter dTC-BPSAF. Carbazole dendrons regulate triplet hybridization, enabling dTC-BPSAF to form near-degenerate lowest triplet (T₁) and high-lying triplet (T₂) states with hybrid local-charge transfer (HLCT) character and large spin-orbit coupling. Integrating dTC-BPSAF into rigid polymers further stabilizes T₂ by suppressing non-radiative decay. Temperature-dependent time-resolved phosphorescence spectra and transient absorption spectra confirm that rigid matrix-based films exhibit thermally activated endothermic T₁→T₂ up-conversion and dual-band anti-Kasha RTP. In contrast, a moderately rigid polymer matrix shows weak T₂ emission, while a soft polymer matrix only produces T₁ emission. This study establishes a dendrimer-matrix synergy strategy combining molecular-level triplet engineering, providing a generalizable approach for efficient anti-Kasha RTP materials and new avenues for advanced photonics.

Keywords

anti-Kasha / dendrimer / room-temperature phosphorescence / triplet up-conversion

References

[1] W. Zhao, Z. He, and B. Z. Tang, “Room-Temperature Phosphorescence From Organic Aggregates,” Nature Reviews Materials 5 (2020): 869–885.

[2] S. Cai, X. Yao, H. Ma, H. Shi, and Z. An, “Manipulating Intermolecular Interactions for Ultralong Organic Phosphorescence,” Aggregate 4 (2023): e320.

[3] J. L. Yu, Z. Chen, Y. Q. Zhu, et al., “Solid-State Room-Temperature Phosphorescence Activated by the End-Capping Strategy of Cyano Groups,” Aggregate 5 (2024): e562.

[4] K. Chang, J. Gu, and L. Yuan, “Achieving Ultrasound-Excited Emission With Organic Mechanoluminescent Materials,” Advanced Materials 36 (2024): e2407875.

[5] B. Zhang, B. Li, H. Zhang, et al., “New Wine in Old Bottles: Fully Substituted Arylthio Effect Realizes High-Efficiency Purely Organic Phosphorescence Light-Emitting Diode With Single and Ultra-Stable Spectra Under 2000 cd m⁻²,” Aggregate 6 (2025): e726.

[6] Z. Shuai, Q. Sun, J. Ren, T. Jiang, and W. Li, “Excited State Structure and Decay Rates for Aggregates,” Aggregate 6 (2025): e70013.

[7] J. Gong, P. Wei, J. Liu, et al., “ASBase: The Universal Database for Aggregate Science,” Aggregate 4 (2023): e263.

[8] J. Guo, J. Fan, L. Lin, et al., “Mechanical Insights Into Aggregation-Induced Delayed Fluorescence Materials With Anti-Kasha Behavior,” Advanced Science 6 (2019): 1801629.

[9] L. Yu, Y. Liu, D. Zhou, Z. Ni, S. Li, and C. Yang, “Aggregation-Induced Anti-Kasha Emission: Unraveling Multimodal Luminescence Mechanisms in a Single Molecule With Five Morphologies,” Aggregate 6 (2025): e70075.

[10] Q. S. Zhang, S. C. Wang, X. H. Xiong, et al., “High-Temperature and Dynamic RGB (Red-Green-Blue) Long-Persistent Luminescence in an Anti-Kasha Organic Compound,” Angewandte Chemie International Edition 61 (2022): e202205556.

[11] T. Wang, A. K. Gupta, S. Wu, A. M. Z. Slawin, and E. Zysman-Colman, “Conjugation-Modulated Excitonic Coupling Brightens Multiple Triplet Excited States,” Journal of the American Chemical Society 145 (2023): 1945–1954.

[12] Y. Gong, Y. Zhou, B. Yue, et al., “Multiwavelength Anti-Kasha's Rule Emission on Self-Assembly of Azulene-Functionalized Persulfurated Arene,” Journal of Physical Chemistry C 123 (2019): 22511–22518.

[13] Z. He, W. Zhao, J. W. Y. Lam, et al., “White Light Emission From a Single Organic Molecule With Dual Phosphorescence at Room Temperature,” Nature Communications 8 (2017): 416.

[14] J. Li, X. Li, G. Wang, et al., “A Direct Observation of Up-Converted Room-Temperature Phosphorescence in an Anti-Kasha Dopant-Matrix System,” Nature Communications 14 (2023): 1987.

[15] J. Zhang, Y. Jin, X. Lu, et al., “Triggering Anti-Kasha Organic Room Temperature Phosphorescence of Clusteroluminescent Materials,” Chemical Science 16 (2025): 7829–7837.

[16] K. Veys and D. Escudero, “Anti-Kasha Fluorescence in Molecular Entities: Central Role of Electron–Vibrational Coupling,” Accounts of Chemical Research 55 (2022): 2698–2707.

[17] C. Li, Z. Lou, L. Hu, et al., “Dendronized Encapsulation With Hierarchical Rigidification Enabling Robust Solution Room-Temperature Phosphorescence, Efficient Electroluminescence and Ultralong Afterglow,” Advanced Science 36 (2025): e11973.

[18] C. Li, M. Wu, Z. Zhao, J. W. Lam, B. Xu, and B. Z. Tang, “Suppressing Molecular Motions: A Pathway to Enhanced Organic Room-Temperature Phosphorescence,” Chem 11 (2025): 102654.

[19] C. Li, Z. Lou, M. Wu, et al., “Achieving Efficient Organic Room-Temperature Phosphorescence Through Acceptor Dendronization,” Journal of the American Chemical Society 147 (2025): 18317–18326.

[20] C. Li, A. K. Harrison, Y. Liu, et al., “Asymmetrical-Dendronized TADF Emitters for Efficient Non-Doped Solution-Processed OLEDs by Eliminating Degenerate Excited States and Creating Solely Thermal Equilibrium Routes,” Angewandte Chemie International Edition 61 (2022): e202115140.

[21] C. Li, A. K. Harrison, Y. Liu, et al., “TADF Dendronized Polymer with Vibrationally Enhanced Direct Spin-Flip Between Charge-Transfer States for Efficient Non-Doped Solution-Processed OLEDs,” Chemical Engineering Journal 435 (2022): 134924.

[22] C. Li, X. Li, X. Luo, et al., “Deep-Red TADF Dendronized Polymer for Efficient Non-Doped Solution-Processed OLEDs,” Journal of Materials Chemistry C 13 (2025): 15628–15633.

[23] T. Lu and F. Chen, “Multiwfn: A Multifunctional Wavefunction Analyzer,” Journal of Computational Chemistry 33 (2012): 580–592.

[24] Z. Liu, T. Lu, and Q. Chen, “An sp-hybridized All-Carboatomic Ring, Cyclo[18]carbon: Electronic Structure, Electronic Spectrum, and Optical Nonlinearity,” Carbon 165 (2020): 461–467.

[25] S. E. Salih, J. K. Oleiwi, and T. A. Mohammed, “Investigation of Hardness and Flexural Properties of PMMA Nano Composites and PMMA Hybrids Nano Composites Reinforced by Different Nano Particles Materials Used in Dental Applications,” Engineering and Technology Journal 34 (2016): 2838–2853.

[26] M. Taşdemir and H. Ö. Gülsoy, “Physical and Mechanical Properties of Iron Powder Filled Polystyrene Composites,” Polymer-Plastics Technology and Engineering 45 (2006): 1207–1211.

[27] C. Pavon, M. Aldas, J. López-Martínez, and S. Ferrándiz, “New Materials for 3D-Printing Based on Polycaprolactone With Gum Rosin and Beeswax as Additives,” Polymers 12 (2020): 334.

[28] J. C. K. de Verney, M. F. S. Lima, and D. M. Lenz, “Properties of SBS and Sisal Fiber Composites: Ecological Material for Shoe Manufacturing,” Materials Research 11 (2008): 447–451.

[29] M. J. Abraham, T. Murtola, R. Schulz, et al., “GROMACS: High Performance Molecular Simulations Through Multi-Level Parallelism From Laptops to Supercomputers,” SoftwareX 1 (2015): 19–25.

[30] D. Zhang, X. Luo, L. Labrador-Páez, et al., “Transparent Programmable Luminescent Tags Enabled by Spiro[fluorene-9,9′-xanthene]-Based Hole-Transporting Molecules,” Journal of Physical Chemistry C 128 (2024): 19893–19900.

[31] F. Ma, B. Wu, S. Zhang, et al., “Lone Pairs-Mediated Multiple Through-Space Interactions for Efficient Room-Temperature Phosphorescence,” Journal of the American Chemical Society 147 (2025): 10803–10814.

[32] N. Jiang, K.-X. Li, J.-J. Wang, et al., “Cluster-Induced Aggregation in Polyurethane Derivatives With Multicolour Emission and Ultra-Long Organic Room Temperature Phosphorescence,” Journal of Materials Chemistry C 12 (2024): 1040–1046.

[33] C. Li, Y. Xu, Y. Liu, Z. Ren, Y. Ma, and S. Yan, “Highly Efficient White-Emitting Thermally Activated Delayed Fluorescence Polymers: Synthesis, Non-Doped White OLEDs and Electroluminescent Mechanism,” Nano Energy 65 (2019): 104057.

[34] C. Li, Z. Ren, X. Sun, H. Li, and S. Yan, “Deep-Blue Thermally Activated Delayed Fluorescence Polymers for Nondoped Solution-Processed Organic Light-Emitting Diodes,” Macromolecules 52 (2019): 2296–2303.

[35] C. Li, Y. Liu, Z. Zhao, J. Liu, Z. Ren, and S. Yan, “Photoluminescent Behaviors of Thermally Activated Delayed Fluorescence Polymeric Emitters in Nanofibers,” Macromolecular Rapid Communications 42 (2021): e2000588.

RIGHTS & PERMISSIONS

2025 The Author(s). Aggregate published by SCUT, AIEI, and John Wiley & Sons Australia, Ltd.