The effect of pH on anthocyanin extraction from Clitoria ternatea L. and polyetherimide polymer membrane electrolyte on the efficiency of dye-sensitized solar cells (DSSCs)

Nita Kusumawati (Department of Chemistry, Universitas Negeri Surabaya, Surabaya 60231, Indonesia)
Pirim Setiarso (Department of Chemistry, Universitas Negeri Surabaya, Surabaya 60231, Indonesia)
Samik Samik (Department of Chemistry, Universitas Negeri Surabaya, Surabaya 60231, Indonesia)
Muhamad Syariffuddien Zuhrie (Department of Electrical Engineering, Universitas Negeri Surabaya, Surabaya 60231, Indonesia)
AR. Sella Auliya (Department of Mathematics, Universitas Islam Darul `Ulum Lamongan, Lamongan 71062, Indonesia)
Khofifatul Rahmawati (Department of Chemistry, Universitas Negeri Surabaya, Surabaya 60231, Indonesia)
Ahmad Naufal Al Hafidl (Department of Chemistry, Universitas Negeri Surabaya, Surabaya 60231, Indonesia)
Muchamad Sabilah Hanafi (Department of Chemistry, Universitas Negeri Surabaya, Surabaya 60231, Indonesia)

Communications in Science and Technology
Vol 11 No 1 (2026)

This present study investigates the effect of pH variation (2-12) on anthocyanin extraction from Clitoria ternatea L. and polyetherimide (PEI) polymer membrane electrolyte performance in dye-sensitized solar cells (DSSCs). The extraction of anthocyanin was conducted through the utilization of microwave-assisted extraction (MAE) at 280 watts for 15 minutes, employing a distilled water ratio of 1:20 ratio. This was followed by a systematic pH conditioning procedure. The characterization employed a range of analytical techniques, including UV-Vis spectrophotometry (400-800 nm), FTIR (4000-500 cm-1), cyclic voltammetry for HOMO-LUMO analysis, SEM (1,000×-10,000× magnification), XRD for crystallinity determination, DSC for thermal stability (60-450°C), and electrochemical impedance spectroscopy. Results obtained demonstrated that pH 4 anthocyanin exhibited maximum dual absorption peaks at 571.21 nm and 612.85 nm, representing the magenta-colored quinoidal base structure with superior light-harvesting capabilities. The FTIR analysis confirmed the presence of stable functional groups, including O-H stretching (3338.08 cm-1), C=O stretching (1710 cm-1), and aromatic C=C (1416.91 cm-1) across all pH conditions without new chemical bond formation. The pH 4 dye demonstrated the narrowest energy bandgap (0.1316 eV) with HOMO at -4.1597 eV and LUMO at -4.0281 eV, optimally aligned with the TiO2 conduction band (-4.0 eV) for efficient electron injection. The PEI membrane exhibited asymmetric morphology with 12.77% crystallinity, a hierarchical porous structure, and excellent thermal stability up to 500°C. The performance of the DSCC reached its maximum at a pH of 4, with efficiency η = 2.37%, Voc = 597 mV, Jsc = 0.0119 mA/cm2, FF = 5.60%, and minimum charge transfer resistance Rct = 100–150 Ω. These findings demonstrate that pH 4 optimization is critical for enhancing the efficiency of DSSC through quinoidal base formation, enhanced molecular conjugation, and accelerated charge transfer processes in environmentally sustainable photovoltaic systems.