Natural solvent facilitated high-shear exfoliated graphene nanoplatelets enabled economically-efficient and stable DSSC

• Published in: Materials letters 2021-03, Vol.287, p.129263, Article 129263
• Main Authors: Nemala, Siva Sankar, Ravulapalli, Sujitha, Kartikay, Purnendu, Banavath, Ramu, Mallick, Sudhanshu, Bhargava, Parag, Bhushan, Mayank, Mohapatra, Debananda
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Charge transfer; Counter electrode; Dye-sensitized solar cells; Electrodes; Electrolytic cells; Exfoliation; Graphene; Graphene nanoplatelets; High shear; Liquid phases; Liquid-phase exfoliation; Materials science; Photovoltaic cells; Platinum; Redox reactions; Shear
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2020.129263

•First-ever successful water-based preparation of graphene nanoplatelets in bulk.•Simple eco-friendly technique using natural graphite in a natural aqueous medium.•Superior electrocatalytic activity and performance towards I−/I3− redox couple.•Higher photovoltaic efficiency (ƞ) of 7.60% compared to the standard Pt, ƞ = 6.95%.•Exceptionally stable ƞ for more than 3000 h under continuous illumination. This work presents an efficient and stable platinum-free shear-exfoliated graphene nanoplatelets (SE-GNP) based counter electrode (CE) for dye-sensitized solar cells (DSSCs). The SE-GNP is prepared by the simple, low cost and eco-friendly high-shear liquid-phase exfoliation technique in bulk using natural graphite flakes as a starting material in an aqueous medium. Detailed electrochemical studies demonstrate that SE-GNP-based CE offers a superior electrocatalytic activity for the redox reaction of I−/I3− redox couple with an improved charge transfer kinetics and the exchange current density at the electrode/electrolyte interface, compared to the standard Pt CE. The SE-GNP-based counter electrode shows exceptionally high stability (>3000 h) and efficiency (ƞ = 7.6%) under constant illumination at a negligible drop in DSSCs' performance.