Effect of pH on Brazilin Extraction from Sappanwood (Caesalpinia sappan L.) and Its Impact on the Efficiency of Natural Dye-Sensitized Solar Cells (DSSCs)
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Keywords:
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Dye-Sensitized Solar Cells (DSSCs), Photovoltaic, Brazilin, Caesalpinia sappan L., pH Variation, Efficiency
Abstract
Dye-sensitized solar cells (DSSCs) are a sustainable photovoltaic technology for addressing the global energy crisis through the conversion of solar energy using photosensitive dyes. This study aims to investigate the effect of pH variation during extraction on the optical, electrochemical, and photovoltaic characteristics of brazilin dye from sappanwood (Caesalpinia sappan L.) for DSSC applications. Brazilian extraction was performed using Microwave-Assisted Extraction (MAE) with pH conditioning from 2 to 12. UV-Vis spectroscopy showed an increase in light absorbance at 400–800 nm. The pH 8 dye exhibited a maximum absorption peak at 444.59 nm due to the formation of a quinoidal base through partial deprotonation of the hydroxyl (-OH) group. FTIR characterization confirmed the chemical structure of the dye with characteristic absorption spectra of broad bands at 3000–3500 cm-1 for the phenolic hydroxyl group and peaks at 2800–3000 cm-1 for aromatic C-H stretching vibrations, as well as aromatic C=C and C=O stretching vibrations at 1600–1400 cm-1. Energy band gap analysis revealed that the dye at pH 2–12 has an energy gap range of 0.1788–0.5355 eV. Optimizing the extraction pH revealed that pH 8 yields the most effective dye performance, resulting in a peak DSSC efficiency of 2.17%, a minimal charge transfer resistance of 100 Ω, and the narrowest energy bandgap at 0.1788 eV. Weakly basic conditions enhance dye molecule conjugation, strengthen bonding with TiO2, and optimize the overall charge transfer process. The research findings confirm the potential of optimizing natural dye extraction conditions as a strategy to enhance DSSC efficiency in a sustainable and environmentally friendly manner.
References
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Kumar, C. and S. N. Patra (2023). Band Gap Prediction of Natural Dyes for Dye Sensitized Solar Cells. In 2023 IEEE 3rd Applied Signal Processing Conference (ASPCON), pages 114–117
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Kusumawati, N., P. Setiarso, Q. A. Hafidha, S. A. Cahyani, and F. F. Fachrirakarsie (2024a). Optimization Thickness of Photoanode Layer and Membrane as Electrolyte Trapping Medium for Improvement Dye-Sensitized Solar Cell Performance. Science and Technology Indonesia, 9(1); 7–16
Kusumawati, N., P. Setiarso, S. Muslim, N. Zakiyah, K. Rahmawati, and F. F. Fachrirakarsie (2024b). Optimizing Dye-Sensitized Solar Cell (DSSC) Performance through Synergistic Natural Dye Combinations from Beta vulgaris L., Curcuma longa L., and Pandanus amaryllifolius. Indonesian Journal of Chemistry, 24(6); 1675–1687
Kusumawati, N., P. Setiarso, A. B. Santoso, S. Muslim, Q. A’yun, and M. M. Putri (2023). Characterization of Poly(vinylidene Fluoride) Nanofiber-Based Electrolyte and Its Application to Dye-Sensitized Solar Cell with Natural Dyes. Indonesian Journal of Chemistry, 23(1); 113–126
Malhotra, S. S., M. Ahmed, M. K. Gupta, and A. Ansari (2024). Metal-Free and Natural Dye-Sensitized Solar Cells: Recent Advancements and Future Perspectives. Sustainable Energy Fuels, 8(18); 4127–4163
Masud, N. and H. K. Kim (2023). Redox Shuttle-Based Electrolytes for Dye-Sensitized Solar Cells: Comprehensive Guidance, Recent Progress, and Future Perspective. ACS Omega, 8(7); 6139–6163
Mejica, G. F. C., Y. Unpaprom, D. Balakrishnan, N. Dussadee, S. Buochareon, and R. Ramaraj (2022). Anthocyanin Pigment-Based Dye-Sensitized Solar Cells with Improved pH-Dependent Photovoltaic Properties. Sustainable Energy Technologies and Assessments, 51; 101971
Mohammadian, J., S. Osfouri, T. Jalali, and A. Jamekhorshid (2024). Electrochemical Impedance Spectroscopy Analysis of Dye-Sensitized Solar Cells Composed of Electrospun Composite Photoanodes: A Comparative Study of Natural and Synthetic Sensitizers. Optik, 303; 171730
Moharam, M. M., A. N. E. Shazly, K. V. Anand, D. E. A. Rayan, M. K. A. Mohammed, M. M. Rashad, and A. E. Halan (2021). Semiconductors as Effective Electrodes for Dye-Sensitized Solar Cell Applications. Topics in Current Chemistry, 379(20); 2–17
Nasyori, A., F. A. Noor, and K. Abidin (2024a). Improved the DSSCs Performance by Sensitizing Eight Natural Dyes and Varying the Annealing Process on the TiO₂. Molecular Crystals and Liquid Crystals, 768(5); 32–46
Nasyori, A., I. I. Patunrengi, and F. A. Noor (2024b). Investigate the Utilization of Novel Natural Photosensitizers for the Performance of Dye-Sensitized Solar Cells (DSSCs). Journal of King Saud University – Science, 36(9); 103423
Okello, A., B. O. Owuor, J. Namukobe, D. Okello, and J. Mwabora (2022). Influence of the pH of Anthocyanins on the Efficiency of Dye-Sensitized Solar Cells. Heliyon, 8(7); e09921
Purba, B. A. V., M. Masendra, R. Pujiarti, and G. Lukmandaru (2024). Contribution of Extractives to the Bark Color of Caesalpinia sappan. Maderas: Ciencia y Tecnología, 26(26); 1–14
Puspitasari, N. D., F. Nurosyid, U. Riyadi, S. D. N. Anisa, and K. Kusumandari (2023). The Impact of Solvent Composition and Copper (Cu) Ion Doping on Dye Anthocyanin on Increasing Dye-Sensitized Solar Cell (DSSC) Efficiency. Indonesian Journal of Applied Physics, 13(2); 193
Rahmawati, K., N. Kusumawati, P. Setiarso, S. Muslim, N. Zakiyah, and F. F. Fachrirakarsie (2025). Optimizing Dye-Sensitized Solar Cell Efficiency with a Triple Blend of Caesalpinia sappan L., Dracaena angustifolia, and Clitoria ternatea L. Molekul, 20(1); 73–85
Setiarso, P., R. V. Harsono, and N. Kusumawati (2023). Fabrication of Dye-Sensitized Solar Cell (DSSC) Using Combination of Dyes Extracted from Curcuma (Curcuma xanthorrhiza) Rhizome and Binahong (Anredera cordifolia) Leaf with Treatment in pH of the Extraction. Indonesian Journal of Chemistry, 23(4); 924–936
Sikder, A., W. Ghann, M. R. Jani, M. T. Islam, S. Ahmed, M. M. Rahman, M. A. M. Patwary, M. Kazi, J. Islam, F. I. Chowdhury, M. A. Yousuf, M. M. Rabbani, M. H. Shariare, and J. Uddin (2023). Characterization and Comparison of DSSCs Fabricated with Black Natural Dyes Extracted from Jamun, Black Plum, and Blackberry. Energies, 16(20); 7187
Syafina, P. and G. Oluleye (2024). A Comparative Assessment of Policy Induced Diffusion Pathways for Utility Scale Solar PV: Case Study of Indonesia. Frontiers in Sustainable Energy Policy, 3; 1308441
Vallejo, W., M. Lerma, and C. Díaz-Uribe (2025). Dye-Sensitized Solar Cells: Meta-Analysis of Effect Sensitizer-Type on Photovoltaic Efficiency. Heliyon, 11(1); e41092
Vij, T., P. P. Anil, R. Shams, K. K. Dash, R. Kalsi, V. K. Pandey, E. Harsanyi, B. Kovacs, and A. M. Shaikh (2023). A Comprehensive Review on Bioactive Compounds Found in Caesalpinia sappan. Molecules, 28(17); 6247
Wirawati, K. T., G. B. Ompusunggu, L. Wardani, and K. R. D. Yanti (2023). The Pharmacological Potential of Sappan Wood (Caesalpinia sappan L.): A Review of Recent Evidence. Pharmacy Reports, 3(3); 86
Wu, X., C. Li, L. Shao, J. Meng, L. Zhang, and G. Chen (2021). Is Solar Power Renewable and Carbon-Neutral: Evidence from a Pilot Solar Tower Plant in China under a Systems View. Renewable and Sustainable Energy Reviews, 138; 110655
Yodha, A. W. M., M. Abdillah, A. Indalifiany, Elfahmi, A. Chahyadi, and Sahidin (2021). Isolasi dan Identifikasi Senyawa Antioksidan dari Ekstrak Metanol Kayu Secang (Caesalpinia sappan). Jurnal Farmasi Sains dan Praktis, 7(3); 214–223 (In Indonesian)
Yuniati, Y., D. D. Azmi, E. Nurandriea, L. Qadariyah, and Mahfud (2023). Parametric Study and Characterization of Sappan Wood (Caesalpinia sappan Linn) Natural Red Colorant Extract with Ultrasonic Assisted Extraction Method. ASEAN Journal of Chemical Engineering, 23(1); 103–112
Zakiyah, N., N. Kusumawati, P. Setiarso, S. Muslim, Q. A’yun, and M. M. Putri (2024). Characterization and Application of Natural Photosensitizer and Poly(vinylidene Fluoride) Nanofiber Membranes-Based Electrolytes in DSSC. Indonesian Journal of Chemistry, 24(3); 701–714
Amin, M., A. Sedyohutomo, N. Amin, A. R. Ibrahim, and I. Mauraji (2025). Ion Chromatographic Analysis of Major Electrolyte Cations in Sappan Wood Extract (Caesalpinia sappan L.). Science and Technology Indonesia, 10(1); 212–220
Amogne, N. Y., D. W. Ayele, and Y. A. Tsigie (2020). Recent Advances in Anthocyanin Dyes Extracted from Plants for Dye Sensitized Solar Cell. Materials for Renewable and Sustainable Energy, 9(23); 2–16
Arkan, F., F. Pakravesh, F. B. Darband, S. Sabagh, and M. Izadyar (2024). Recent Progress Toward High-Performance Dye-Sensitized Solar Cells: A Review. Journal of the Iranian Chemical Society, 21; 577–638
Arsyad, W. S., R. Suhardiman, I. Usman, L. Aba, S. Suryani, L. O. A. N. Ramadhan, M. Nurdin, and R. Hidayat (2024). Improvement of Dye-Sensitized Solar Cells (DSSCs) Performance Using Crude Brazilein Extract from Sappan Wood (Caesalpinia sappan L.) with the Incorporation of ZnO Nanoparticles. Journal of Molecular Structure, 1303; 137548
Cavalluzzi, M. M., A. Lamonaca, N. P. Rotondo, D. V. Miniero, M. Muraglia, P. Gabriele, F. Corbo, A. D. Palma, R. Budriesi, E. D. Angelis, L. Monaci, and G. Lentini (2022). Microwave-Assisted Extraction of Bioactive Compounds from Lentil Wastes: Antioxidant Activity Evaluation and Metabolomic Characterization. Molecules, 27(21)
Estiningtyas, I. W., N. Kusumawati, P. Setiarso, S. Muslim, N. T. Rahayu, R. N. Safitri, N. Zakiyah, and F. F. Fachrirakarsie (2023). Effect of Natural Dye Combination and pH Extraction on the Performance of Dye-Sensitized Photovoltaics Solar Cell. International Journal of Renewable Energy Development, 12(6); 1054–1060
Holechek, J. L., H. M. E. Geli, M. N. Sawalhah, and R. Valdez (2022). A Global Assessment: Can Renewable Energy Replace Fossil Fuels by 2050? Sustainability, 14(8); 4792
Kim, W. S., S. J. Park, T. G. Hwang, H. M. Kim, H. K. Lee, S. Kim, W. J. Choi, J. H. Yoon, Y. S. Kim, D. J. Lee, S. H. Jang, J. Y. Kim, and J. P. Kim (2024). Enhancing the Reliability of Dyes for Color Filters Through TiO₂ Adsorption: Comprehensive Identification of Factors Affecting Photocatalysis. Materials Advances, 5(5); 1917–1929
Kumar, C. and S. N. Patra (2023). Band Gap Prediction of Natural Dyes for Dye Sensitized Solar Cells. In 2023 IEEE 3rd Applied Signal Processing Conference (ASPCON), pages 114–117
Kurniawan, M. R. H., S. A. Cahyani, N. Kusumawati, P. Setiarso, and S. Muslim (2025). Optimization of Radiation and Electric Current Storage in a Dye-Sensitized Solar-Cell System Based FTO/TiO₂/Acy/PVDF/C/FTO Modules for Electrical Equipment Applications. Science and Technology Indonesia, 10(2); 574–587
Kusumawati, N., P. Setiarso, Q. A. Hafidha, S. A. Cahyani, and F. F. Fachrirakarsie (2024a). Optimization Thickness of Photoanode Layer and Membrane as Electrolyte Trapping Medium for Improvement Dye-Sensitized Solar Cell Performance. Science and Technology Indonesia, 9(1); 7–16
Kusumawati, N., P. Setiarso, S. Muslim, N. Zakiyah, K. Rahmawati, and F. F. Fachrirakarsie (2024b). Optimizing Dye-Sensitized Solar Cell (DSSC) Performance through Synergistic Natural Dye Combinations from Beta vulgaris L., Curcuma longa L., and Pandanus amaryllifolius. Indonesian Journal of Chemistry, 24(6); 1675–1687
Kusumawati, N., P. Setiarso, A. B. Santoso, S. Muslim, Q. A’yun, and M. M. Putri (2023). Characterization of Poly(vinylidene Fluoride) Nanofiber-Based Electrolyte and Its Application to Dye-Sensitized Solar Cell with Natural Dyes. Indonesian Journal of Chemistry, 23(1); 113–126
Malhotra, S. S., M. Ahmed, M. K. Gupta, and A. Ansari (2024). Metal-Free and Natural Dye-Sensitized Solar Cells: Recent Advancements and Future Perspectives. Sustainable Energy Fuels, 8(18); 4127–4163
Masud, N. and H. K. Kim (2023). Redox Shuttle-Based Electrolytes for Dye-Sensitized Solar Cells: Comprehensive Guidance, Recent Progress, and Future Perspective. ACS Omega, 8(7); 6139–6163
Mejica, G. F. C., Y. Unpaprom, D. Balakrishnan, N. Dussadee, S. Buochareon, and R. Ramaraj (2022). Anthocyanin Pigment-Based Dye-Sensitized Solar Cells with Improved pH-Dependent Photovoltaic Properties. Sustainable Energy Technologies and Assessments, 51; 101971
Mohammadian, J., S. Osfouri, T. Jalali, and A. Jamekhorshid (2024). Electrochemical Impedance Spectroscopy Analysis of Dye-Sensitized Solar Cells Composed of Electrospun Composite Photoanodes: A Comparative Study of Natural and Synthetic Sensitizers. Optik, 303; 171730
Moharam, M. M., A. N. E. Shazly, K. V. Anand, D. E. A. Rayan, M. K. A. Mohammed, M. M. Rashad, and A. E. Halan (2021). Semiconductors as Effective Electrodes for Dye-Sensitized Solar Cell Applications. Topics in Current Chemistry, 379(20); 2–17
Nasyori, A., F. A. Noor, and K. Abidin (2024a). Improved the DSSCs Performance by Sensitizing Eight Natural Dyes and Varying the Annealing Process on the TiO₂. Molecular Crystals and Liquid Crystals, 768(5); 32–46
Nasyori, A., I. I. Patunrengi, and F. A. Noor (2024b). Investigate the Utilization of Novel Natural Photosensitizers for the Performance of Dye-Sensitized Solar Cells (DSSCs). Journal of King Saud University – Science, 36(9); 103423
Okello, A., B. O. Owuor, J. Namukobe, D. Okello, and J. Mwabora (2022). Influence of the pH of Anthocyanins on the Efficiency of Dye-Sensitized Solar Cells. Heliyon, 8(7); e09921
Purba, B. A. V., M. Masendra, R. Pujiarti, and G. Lukmandaru (2024). Contribution of Extractives to the Bark Color of Caesalpinia sappan. Maderas: Ciencia y Tecnología, 26(26); 1–14
Puspitasari, N. D., F. Nurosyid, U. Riyadi, S. D. N. Anisa, and K. Kusumandari (2023). The Impact of Solvent Composition and Copper (Cu) Ion Doping on Dye Anthocyanin on Increasing Dye-Sensitized Solar Cell (DSSC) Efficiency. Indonesian Journal of Applied Physics, 13(2); 193
Rahmawati, K., N. Kusumawati, P. Setiarso, S. Muslim, N. Zakiyah, and F. F. Fachrirakarsie (2025). Optimizing Dye-Sensitized Solar Cell Efficiency with a Triple Blend of Caesalpinia sappan L., Dracaena angustifolia, and Clitoria ternatea L. Molekul, 20(1); 73–85
Setiarso, P., R. V. Harsono, and N. Kusumawati (2023). Fabrication of Dye-Sensitized Solar Cell (DSSC) Using Combination of Dyes Extracted from Curcuma (Curcuma xanthorrhiza) Rhizome and Binahong (Anredera cordifolia) Leaf with Treatment in pH of the Extraction. Indonesian Journal of Chemistry, 23(4); 924–936
Sikder, A., W. Ghann, M. R. Jani, M. T. Islam, S. Ahmed, M. M. Rahman, M. A. M. Patwary, M. Kazi, J. Islam, F. I. Chowdhury, M. A. Yousuf, M. M. Rabbani, M. H. Shariare, and J. Uddin (2023). Characterization and Comparison of DSSCs Fabricated with Black Natural Dyes Extracted from Jamun, Black Plum, and Blackberry. Energies, 16(20); 7187
Syafina, P. and G. Oluleye (2024). A Comparative Assessment of Policy Induced Diffusion Pathways for Utility Scale Solar PV: Case Study of Indonesia. Frontiers in Sustainable Energy Policy, 3; 1308441
Vallejo, W., M. Lerma, and C. Díaz-Uribe (2025). Dye-Sensitized Solar Cells: Meta-Analysis of Effect Sensitizer-Type on Photovoltaic Efficiency. Heliyon, 11(1); e41092
Vij, T., P. P. Anil, R. Shams, K. K. Dash, R. Kalsi, V. K. Pandey, E. Harsanyi, B. Kovacs, and A. M. Shaikh (2023). A Comprehensive Review on Bioactive Compounds Found in Caesalpinia sappan. Molecules, 28(17); 6247
Wirawati, K. T., G. B. Ompusunggu, L. Wardani, and K. R. D. Yanti (2023). The Pharmacological Potential of Sappan Wood (Caesalpinia sappan L.): A Review of Recent Evidence. Pharmacy Reports, 3(3); 86
Wu, X., C. Li, L. Shao, J. Meng, L. Zhang, and G. Chen (2021). Is Solar Power Renewable and Carbon-Neutral: Evidence from a Pilot Solar Tower Plant in China under a Systems View. Renewable and Sustainable Energy Reviews, 138; 110655
Yodha, A. W. M., M. Abdillah, A. Indalifiany, Elfahmi, A. Chahyadi, and Sahidin (2021). Isolasi dan Identifikasi Senyawa Antioksidan dari Ekstrak Metanol Kayu Secang (Caesalpinia sappan). Jurnal Farmasi Sains dan Praktis, 7(3); 214–223 (In Indonesian)
Yuniati, Y., D. D. Azmi, E. Nurandriea, L. Qadariyah, and Mahfud (2023). Parametric Study and Characterization of Sappan Wood (Caesalpinia sappan Linn) Natural Red Colorant Extract with Ultrasonic Assisted Extraction Method. ASEAN Journal of Chemical Engineering, 23(1); 103–112
Zakiyah, N., N. Kusumawati, P. Setiarso, S. Muslim, Q. A’yun, and M. M. Putri (2024). Characterization and Application of Natural Photosensitizer and Poly(vinylidene Fluoride) Nanofiber Membranes-Based Electrolytes in DSSC. Indonesian Journal of Chemistry, 24(3); 701–714
Authors
Al Hafidl, A. N., Nita Kusumawati, Pirim Setiarso, Samik, S., Maria Monica Sianita Basukiwardojo, & Khofifatul Rahmawati. (2026). Effect of pH on Brazilin Extraction from Sappanwood (Caesalpinia sappan L.) and Its Impact on the Efficiency of Natural Dye-Sensitized Solar Cells (DSSCs). Science and Technology Indonesia, 11(2), 378–388. https://doi.org/10.26554/sti.2026.11.2.378-388
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