INVESTIGATION OF N719 DYE ADSORPTION ON NANOPARTICLE TIO2 AEROXIDE P25 AS A PHOTOANODE FOR DYE-SENSITIZED SOLAR CELL (DSSC)

• Main Author: Nur Amalina, Auliya
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/51979
• Institution: Institut Teknologi Bandung

Dye-Sensitized Solar Cell (DSSC) is the third generation of solar cells and an alternative to the silicon-based solar cell. The simple fabrication process and low- cost production compare to the silicon-based solar cell have caught wide attention. The main part of DSSC that distinguishes from other solar cells is the sensitizer or dye on the working electrode or photoanode. The sensitizer molecules are chemically bonded to the oxide semiconductor, the TiO2 nanoparticles. One of the most outstanding sensitizers is N719 (Ruthenizer 535-bis TBA), a ruthenium-based complex dye. The sensitizer on the photoanode plays a vital role in generating the electron flow on DSSC when adsorbed the sunlight. The adsorption of the N719 molecules on the TiO2 Aeroxide P25 nanoparticles' surface has not been well reported. Thus, its adsorption behavior becomes a big question, especially when it relates to DSSC performance. The adsorption of the N719 molecule on nanoparticle TiO2 was confirmed to be chemisorption via the carboxylate groups observed by Raman spectroscopy as the COO- vibration modes at 1267 and 1609 cm-1. The FESEM images show that the average particle size of TiO2 nanoparticles increases with the N719 adsorption. The average particle size increases from 25 to 30 nm due to the presence of adsorbed N719 molecule on the TiO2 nanoparticle surface. The determination of N719 molecule adsorbed on the nanoparticle TiO2 surface is by the washing method and the depletion method, further characterized by UV-Vis spectrophotometry. The washing method shows that the adsorbed N719 molecules increases with the adsorption time up to 18 hours and then subsequently reached saturation with no significant increase for longer adsorption time. The washing method's concentration variation shows an increase of the adsorbed N719 molecules for concentration from 5 × 10-6 M up to 5 × 10-4 M until reached saturation at 2 × 10-3 M. Higher concentration gives no significant increase in the adsorbed N719 molecules. However, the depletion method shows a fluctuating trend due to the ethanol solvent's volatile nature, which directly influences the residual immersion concentration. The absorbance spectra from the washing procedure were normalized and resulted in a blue shift, indicating aggregation formation at higher concentration. Several adsorption isotherm models were applied to fit the N719 adsorption data. Langmuir model is the best-fit to the adsorption data, with the N719 molecules grow up to a finite thickness on the surface of TiO2 nanoparticles. The DSSC performance tends to increase with N719 concentration until saturation. The DSSC efficiency rises from 0.83% at 5 × 10-6 M to 3.00% at 5 × 10-4 M, and stabilizing around 3% until the highest concentration. The performance of DSSC was strongly affected by the number of adsorbed N179 molecules. The comparison between the DSSC efficiency and the adsorption data shows two different regimes indicating dye-aggregates' formation.