Use of Ascorbic Acid Linker in Enhancing the Photovoltaic Performance of CdS/TiO2 Quantum Dot Sensitized Solar Cells

Abstract

This study explores the use of ascorbic acid to enhance the photovoltaic performance of CdS/TiO2 Quantum Dot Sensitized Solar Cells (QDSSCs). Ascorbic acid acts as a mild reducing agent, donating electrons to Ti atoms on the TiO2 film, effectively filling oxygen vacancies known to act as recombination centers for photogenerated charge carriers. By passivating these detrimental sites, ascorbic acid facilitates improved carrier transport and reduces recombination, ultimately boosting photocurrent and overall efficiency. QDSSCs fabricated via the Successive Ionic Layer Adsorption and Reaction (SILAR) method were characterized using I-V measurements, Incident Photon to Current Conversion Efficiency (IPCE), Impedance Spectroscopy (IS), and overall power conversion efficiency. The optimized cell incorporated with ascorbic acid demonstrated a remarkable improvement compared to the control, achieving a short circuit current density (Jsc) of 4.863 mA/cm², open circuit voltage (Voc) of 446.1mV, efficiency of 1.368%, fill factor of 24.6%, and maximum power of 0.342mW. Optimization of ascorbic acid absorption time and precursor concentrations resulted an impressive 68.26% enhancement in efficiency (from 0.813% to 1.368%) and increase in maximum power from 0.163 mW to 0.342 mW for 0.64 cm². cell. This study highlights the potential of ascorbic acid as a simple and effective strategy for enhancing the performance of CdS/TiO2 QDSSCs, paving the way for further developments in low-cost and efficient solar cell technologies.