Azulene-BODIPY Hybrid Dyes as Non-Emissive, Wide-Gamut RGB Colorants for High-Resolution Color Filters

Abstract

The pursuit of high-performance color filters (CFs) for next-generation displays demands organic dyes with a wide color gamut, high color purity, low emissivity, and excellent processability. Herein, we report a rational molecular design strategy by integrating the nonalternant, polar azulene unit into the BODIPY scaffold to create three novel derivatives—AzBdpy-B, AzBdpy-G, and AzBdpy-R—tailored for blue, green, and red subpixel applications. By strategically varying the linkage sites (azulene 1-/2-positons to BODIPY α/β positions), we precisely modulate intramolecular charge transfer (ICT) strength and frontier molecular orbital hybridization. This achieves targeted absorption peaks at 621 nm (AzBdpy-B), 735 nm (AzBdpy-G), and 535 nm (AzBdpy-R), respectively. The incorporation of azulene not only enables broad spectral tunability but also effectively suppresses radiative decay, resulting in near-zero visible fluorescence—critical for minimizing background luminance in CFs. CFs fabricated from these materials demonstrate good photothermal stability (ΔE_ab < 3 after 150°C heating and UV exposure), high color purity, and wide sRGB coverage (81%), with photolithographic resolution down to 8.2-10.7 µm. Combined experimental and theoretical analyses—including single-crystal X-ray diffraction, hole-electron distribution, and Independent Gradient Model (IGM)—reveal how azulene-BODIPY electronic coupling governs both optical performance and structural robustness. This work establishes azulene-functionalized BODIPYs as a promising platform for high-resolution, low-emissivity RGB color photoresists, offering new insights into the molecular engineering of advanced dye-based optoelectronic materials.

Keywords

azulene-BODIPY hybrid dyes / color filter / wide-gamut RGB colorants

References

[1] J. Li, Y. Yin, and H. Meng, “Research Progress of Color Photoresists for TFT-LCD,” Dyes and Pigments 225 (2024): 112094.

[2] H. Xiaoming, Z. Caijun, S. Fengwei, et al., “J-Aggregation Strategy Toward Potentiated NIR-II Fluorescence Bioimaging of Molecular Fluorophores,” Advanced Materials 36 (2024): 2304848.

[3] C. Deukseok, S. Changgyun, S. Byonggwon, et al., “Color Filters for Reflective Display With Wide Viewing Angle and High Reflectivity Based on Metal Dielectric Multilayer,” Applied Physics Letters 101 (2012): 221120.

[4] E. Panchenko, L. Wesemann, D. E. Gómez, T. D. James, T. J. Davis, and A. Roberts, “Ultracompact Camera Pixel With Integrated Plasmonic Color Filters,” Advanced Optical Materials 7 (2019): 1900893.

[5] L. Hou, T. Wang, S. Yu, X. Xu, and X. Yu, “Multiresponsive Color-Tunable Phosphorescence With Matrix-Confined Clusters,” Aggregate 6 (2025): e70071.

[6] B. Liu, G. Huang, Y. Wang, et al., “Highly Photoluminescent RGB-Carbon Dots and Their Integration Applications in Light-Emitting Diodes and Luminescent Solar Concentrators,” Aggregate 6 (2025): e70167.

[7] H. D. Cheng, X. H. Jiang, Y. Sun, and J. L. Wang, “Color Image Segmentation: Advances and Prospects,” Pattern Recognition 34 (2001): 2259-2281.

[8] C. Jun, L. Woosung, S. Chun, Y. Sim Bum, S. P. Jong, and K. Jae Pil, “Facile Synthesis and Characterization of Novel Coronene Chromophores and Their Application to LCD Color Filters,” Dyes and Pigments 94 (2012): 34-39.

[9] Z. Li and H. R. Allcock, “Polyphosphazenes With Immobilized Dyes as Potential Color Filter Materials,” ACS Applied Materials & Interfaces 7 (2015): 13518-13523.

[10] X. Runfeng, Y. Letao, Y. Bo, et al., “An Integrated Design Strategy of Zinc Phthalocyanine Dyes for LCD Dye-Based Color Filters,” Dyes and Pigments 219 (2023): 111562.

[11] S. H. Jang, G. Lee, Y. J. Han, et al., “Synthesis and Characterisation of Dimeric Triphenylmethane Water-Soluble Dyes for High-Speed Inkjet Printing,” Dyes and Pigments 196 (2021): 109737.

[12] J. Hyocheol, S. K. Nam, K. Beomjin, et al., “Development of Cross-Linkable Dimeric Triarylmethine Derivatives With Improved Thermal and Solvent Stability for Color Filters,” Dyes and Pigments 149 (2018): 336-340.

[13] S. Chun, D. K. Young, C. Jae-Hong, Y. Chun, and K. Jae Pil, “The Synthesis of Thermally-Stable Red Dyes for LCD Color Filters and Analysis of Their Aggregation and Spectral Properties,” Dyes and Pigments 88 (2011): 166-173.

[14] Y. K. Jeong, S. Chun, C. Sang, et al., “The Effect of Fluorescence of Perylene Red Dyes on the Contrast Ratio of LCD Color Filters,” Dyes and Pigments 131 (2016): 293.

[15] C. Jun, H. K. Se, L. Woosung, et al., “The Influence of Aggregation Behavior of Novel Quinophthalone Dyes on Optical and Thermal Properties of LCD Color Filters,” Dyes and Pigments 101 (2014): 186-195.

[16] Y. Ren, R. Xu, W. Wang, P. Chen, and X. Peng, “Synthesis and Stability Study of Anthraquinone Dyes for Color Photoresist,” CIESC Journal 73 (2022): 2251-2261.

[17] S. K. Rangaraju and S. Young-A, “Synthesis, Photophysical and Aggregation Properties of Novel Phenanthrene and Pyrene Substituted Phthalocyanines,” Korean Chemical Engineering Research 56 (2018): 792-797.

[18] B. Gopal and S. P. Jong, “Enhanced Solution Processing and Optical Properties of Perhalogenated Zinc-Phthalocyanines via Anion-π Bonding,” Dyes and Pigments 201 (2022): 110199.

[19] Y. K. Jeong, S. Chun, C. Jun, et al., “Synthesis and Characterization of Novel Perylene Dyes With New Substituents at Terminal-Position as Colorants for LCD Color Filter,” Journal of Inclusion Phenomena and Macrocyclic Chemistry 82 (2015): 203-212.

[20] W. N. Jin, M. K. Hong, H. K. Se, B. Y. Sim, C. Jun, and P. K. Jae, “Synthesis and Characterization of Metal Phthalocyanine Bearing Carboxylic Acid Anchoring Groups for Nanoparticle Dispersion and Their Application to Color Filters,” Dyes and Pigments 184 (2021): 108737.

[21] W. N. Jin, H. K. Se, C. Sei-Won, H. K. Young, S. K. Moo, and P. K. Jae, “Aryloxy- and Chloro-Substituted Zinc(II) Phthalocyanine Dyes: Synthesis, Characterization, and Application for Reducing the Thickness of Color Filters,” Dyes and Pigments 154 (2018): 128-136.

[22] C. Jun, H. K. Se, L. Woosung, Y. Chun, and P. K. Jae, “Synthesis and Characterization of Thermally Stable Dyes With Improved Optical Properties for Dye-Based LCD Color Filters,” New Journal of Chemistry 36 (2012): 812-818.

[23] M. Sarker, S. Shin, J. H. Jeong, and S. H. Jhung, “Mesoporous Metal-Organic Framework PCN-222(Fe): Promising Adsorbent for Removal of Big Anionic and Cationic Dyes From Water,” Chemical Engineering Journal 371 (2019): 252-259.

[24] C. Jun, L. Woosung, W. N. Jin, K. Tae-Min, and P. K. Jae, “Synthesis and Characterization of Novel Triazatetrabenzcorrole Dyes for LCD Color Filter and Black Matrix,” Dyes and Pigments 99 (2013): 357-365.

[25] Y. Y. Zhao, X. Zhang, Z. Chen, et al., “Supramolecular Phthalocyanine Assemblies-Enhanced Synergistic Photodynamic and Photothermal Therapy Guided by Photoacoustic Imaging,” Aggregate 5 (2024): e514.

[26] J. Ding, D. Wu, J. Zhu, et al., “High-Entropy Carbons: From High-Entropy Aromatic Species to Single-Atom Catalysts for Electrocatalysis,” Chemical Engineering Journal 426 (2021): 131320.

[27] C. Duan, J. Zhang, J. Xiang, X. Yang, and X. Gao, “Azulene-Embedded [n]Helicenes (n = 5, 6 and 7),” Angewandte Chemie International Edition 61 (2022): e202201494.

[28] R. Liu, Y. Fu, F. Wu, et al., “Modular Synthesis of Structurally Diverse Azulene-Embedded Polycyclic Aromatic Hydrocarbons by Knoevenagel-Type Condensation,” Angewandte Chemie International Edition 62 (2023): e202219091.

[29] H. Luo and J. Liu, “Facile Synthesis of Nitrogen-Doped Nanographenes With Joined Nonhexagons via a Ring Expansion Strategy,” Angewandte Chemie International Edition 62 (2023): e202302761.

[30] A. Ong, T. Tao, Q. Jiang, et al., “Azulene-Fused Acenes,” Angewandte Chemie International Edition 61 (2022): e202209286.

[31] L. Qin, Y. Y. Huang, B. Wu, et al., “Diazulenorubicene as a Non-Benzenoid Isomer of Peri-Tetracene With Two Sets of 5/7/5 Membered Rings Showing Good Semiconducting Properties,” Angewandte Chemie International Edition 62 (2023): e202304632.

[32] S. Wang, M. Tang, L. Wu, et al., “Linear Nonalternant Isomers of Acenes Fusing Multiple Azulene Units,” Angewandte Chemie International Edition 61 (2022): e202205658.

[33] D. E. Lynch and D. G. Hamilton, “The History of Azulenyl Squaraines,” Australian Journal of Chemistry 70 (2017): 857-871.

[34] J. Guo, F. Du, B. Yu, et al., “Heptacyclic Aromatic Hydrocarbon Isomers With Two Azulene Units Fused,” Chemical Science 15 (2024): 12589-12597.

[35] H. Xin, J. Li, R.-Q. Lu, X. Gao, and T. M. Swager, “Azulene-Pyridine-Fused Heteroaromatics,” Journal of the American Chemical Society 142 (2020): 13598-13605.

[36] M. Murai, S. Iba, H. Ota, and K. Takai, “Azulene-Fused Linear Polycyclic Aromatic Hydrocarbons With Small Bandgap, High Stability, and Reversible Stimuli Responsiveness,” Organic Letters 19 (2017): 5585-5588.

[37] V. Koen and E. Daniel, “Anti-Kasha Fluorescence in Molecular Entities: Central Role of Electron−Vibrational Coupling,” Accounts of Chemical Research 55 (2022): 2698-2707.

[38] D. Dunlop, L. Ludvíková, A. Banerjee, H. Ottosson, and T. Slanina, “Excited-State (Anti)Aromaticity Explains Why Azulene Disobeys Kasha's Rule,” Journal of the American Chemical Society 145 (2023): 21569-21575.

[39] H. Gao, Y. Yao, C. Li, et al., “Fused Azulenyl Squaraine Derivatives Improve Phototheranostics in the Second Near-Infrared Window by Concentrating Excited State Energy on Non-Radiative Decay Pathways,” Angewandte Chemie International Edition 63 (2024): e202400372.

[40] Z. A. Li, K. L. Zhu, J. Liang, and H. Y. Gong, “Covalent Bond Regulation in Nanographene: En Route to Precise Aggregation State Modification,” Aggregate 6 (2025): e70147.

[41] G. Lizhi, C. Jingzhi, Z. Yue, M. John, L. Hua, and S. Zhen, “Synthesis and Properties of Azulene-Functionalized BODIPYs,” RSC Advances 6 (2016): 32124.

[42] J.-I. Kitai, T. Kobayashi, W. Uchida, et al., “Photochromism of a Diarylethene Having an Azulene Ring,” Journal of Organic Chemistry 77 (2012): 3270-3276.

[43] J. Zhang and S. Petoud, “Azulene-Moiety-Based Ligand for the Efficient Sensitization of Four Near-Infrared Luminescent Lanthanide Cations: Nd³⁺, Er³⁺, Tm³⁺, and Yb³⁺,” Chemistry: A European Journal 14 (2008): 1264-1272.

[44] Y. Yao, X. Sun, Z. Zhang, et al., “Azulene-Containing Bis(Squaraine) Dyes: Design, Synthesis and Aggregation Behaviors,” Chemistry: A European Journal 30 (2024): e202400474.

[45] Y. Yao, H. Lin, S. Cai, X. Yang, and X. Gao, “Single-Bond-Linked and Vinylene-Bridged Azulenyl Bis(Squaraine) Dyes: Design, Synthesis and Molecular Self-Assembly Behaviors,” Organic Chemistry Frontiers 11 (2024): 7059-7068.

[46] S. S. Zhao, X.-P. Guo, X.-H. Pan, Y. B. Huang, and R. Cao, “An “All in One” Strategy to Boost Antibacterial Phototherapy via Porphyrin and Boron Dipyrromethenes Based Covalent Organic Framework,” Chemical Engineering Journal 457 (2023): 141017.

[47] L. Ding, Z. Tian, J. Hou, et al., “Sensing Carboxylesterase 1 in Living Systems by a Practical and Isoform-Specific Fluorescent Probe,” Chinese Chemical Letters 30 (2019): 558-562.

[48] W. Feng, Y. Lv, Z. Chen, et al., “A Carrier-Free Multifunctional Nano Photosensitizer Based on Self-Assembly of Lactose-Conjugated BODIPY for Enhanced Anti-Tumor Efficacy of Dual Phototherapy,” Chemical Engineering Journal 417 (2021): 129178.

[49] G. Duran-Sampedro, A. R. Agarrabeitia, I. Garcia-Moreno, et al., “Chlorinated BODIPYs: Surprisingly Efficient and Highly Photostable Laser Dyes,” European Journal of Organic Chemistry 2012 (2012): 6335-6350.

[50] L. Aurore and B. Kevin, “BODIPY Dyes and Their Derivatives: Syntheses and Spectroscopic Properties,” Chemical Reviews 107 (2007): 4891.

[51] Y. Song, X. Tong, Y. Han, and Q. W. Zhang, “Finely Tunable NIR-II Organic Scaffolds for Fluorescence/Photoacoustic Duplex Imaging-Guided Noninvasive Photothermal Therapy of Glioblastoma,” Aggregate 6 (2025): e680.

[52] S. Wang, X. Bi, H. Zhu, X. Ji, H. Lu, and Z. Shen, “Rational Design of Aggregation-Induced Emission-Active Bisboron Complexes (BOQHYs) for High-Fidelity Lipid Droplet Imaging,” Aggregate 6 (2025): e670.

[53] A. B. Nepomnyashchii, M. Bröring, J. Ahrens, and A. J. Bard, “Synthesis, Photophysical, Electrochemical, and Electrogenerated Chemiluminescence Studies. Multiple Sequential Electron Transfers in BODIPY Monomers, Dimers, Trimers, and Polymer,” Journal of the American Chemical Society 133, (2011): 8633-8645.

[54] W. Dan and F. O. S. Donal, “Synthesis and Properties of BF₂‑3,3-Dimethyldiarylazadipyrromethene Near-Infrared Fluorophores,” Organic Letters 15 (2013): 3392-3395.

[55] A. Wakamiya, T. Murakamib, and S. Yamaguchi, “Benzene-Fused BODIPY and Fully-Fused BODIPY Dimer: Impacts of the Ring-Fusing at the b Bond in the BODIPY Skeleton,” Chemical Science 4 (2013): 1002-1007.

[56] H. Xin, B. Hou, and X. Gao, “Azulene-Based π-Functional Materials: Design, Synthesis, and Applications,” Accounts of Chemical Research 54 (2021): 1737-1753.

[57] F. V. Edward, C. Veaceslav, A. D. S. F. Demetrio, S. Seyhan, and B. D. Jean-Luc, “Effect of Electronic Polarization on Charge-Transport Parameters in Molecular Organic Semiconductors,” Journal of the American Chemical Society 128 (2006): 9882.

[58] X. Tang, L.-S. Cui, H.-C. Li, et al., “Highly Efficient Luminescence From Space-Confined Charge-Transfer Emitters,” Nature Materials 19 (2020): 1332-1338.

[59] R. K. Neha, R. A. Abhijeet, D. Sashi, C. Aditya, and S. Z. Sanjio, “Effect of Connectivity Variation in Azulene-BODIPY Triads and Their Optoelectronic Properties,” New Journal of Chemistry 47 (2023): 2456-2463.

[60] Q. Zhou, Y. Guo, and Y. Zhu, “Photocatalytic Sacrificial H₂ Evolution Dominated by Micropore-Confined Exciton Transfer in Hydrogen-Bonded Organic Frameworks,” Nature Catalysis 6 (2023): 574-584.

[61] J. Yuan, Y. Yuan, X. Tian, Y. Liu, and J. Sun, “Insights Into the Photobehavior of Fluorescent Oxazinone, Quinazoline, and Difluoroboron Derivatives: Molecular Design Based on the Structure-Property Relationships,” Journal of Physical Chemistry C 121 (2017): 8091-8108.

[62] T. Lu and Q. Chen, “Independent Gradient Model Based on Hirshfeld Partition: A New Method for Visual Study of Interactions in Chemical Systems,” Journal of Computational Chemistry 43 (2022): 539-555.

[63] C. Lefebvre, G. Rubez, H. Khartabil, J. C. Boisson, J. Contreras-Garcia, and E. Henon, “Accurately Extracting the Signature of Intermolecular Interactions Present in the NCI Plot of the Reduced Density Gradient Versus Electron Density,” Physical Chemistry Chemical Physics 19 (2017): 17928-17936.

[64] K. Musun, K. Younghoon, H. Sanghun, et al., “Past, Present, and Future of WCG Technology in Display,” Journal of the Society for Information Display 27 (2019): 691-699.

[65] M. Shih-Hsin, L. Chi-Hung, and T. An-Ching, “LED Collimation Module for Time Sequential Back Light System,” Journal of Display Technology 10 (2014): 1036-1041.

[66] L. Wei-Ting and H. Wen-Yao, “Enhancing the Color Gamut of White Displays Using Novel Deep-Blue Organic Fluorescent Dyes to Form Color-Changed Thin Films With Improved Efficiency,” Optical Engineering 51 (2012): 104001.

[67] Y. Namkyung, Y. L. Jee, K. Se Hun, K. Doyeon, Y. J. Jae, and L. Woosung, “A Study on Red Cyanine Dyes Employing Bis(Fluorosulfonyl)Imide Anions for Color Filters of Virtual and Augmented Reality Displays,” Dyes and Pigments 220 (2023): 111734.

[68] W. Wanying, Y. Qichao, X. Runfeng, W. Ankang, C. Pengzhong, and P. Xiaojun, “Novel Zinc(II) Phthalocyanine Dyes for Color Photoresists,” Synlett 35 (2024): 118-124.

[69] H. Sugita, S. Ebata, H. Suzuki, et al., “Polyvinyl-Alcohol-Based Color Resist for Low-Temperature Color-Filter Production,” Displays 77 (2023): 102393.

RIGHTS & PERMISSIONS

2026 The Author(s). Aggregate published by SCUT, AIEI, and John Wiley & Sons Australia, Ltd.