Boosting the performance of dye-sensitized solar cells by employing Li-substituted NiO nanosheets as highly efficient electrocatalysts for reduction of triiodide.

Abstract

Dye-sensitized solar cells (DSSCs) exhibit considerable potential as a promising technology, particularly when addressing the challenge of replacing the costly Platinum (Pt) counter electrode (CE) with economically viable and chemically stable CE materials. This study examines the use of two-dimensional hexagonal-shaped nickel oxide nanosheets substituted with varying mol% of lithium (1, 3, and 5%) (Li (1-5%)-NiO NSs) as the counter electrode (CEs) for DSSCs. The facile hydrothermal method was employed for the preparation of NiO and Li (1-5 mol%)-NiO samples. The BET analysis of NiO and Li (1-5%)-NiO indicates that higher concentrations of Li¹⁺ ions in Ni²⁺ ions sites lead to an increase in the overall surface area of NiO. This leads to an elevated number of exposed electrocatalytic active sites which resulted in enhancing the rate of reduction of $$ ions. The cyclic voltammetry (CV) result of 5 mol% of Li substituted NiO (5-LNO) shows outstanding electrocatalytic activity towards the redox reaction of $$ redox mediator among the as-prepared CEs. The DSSCs assembled with 5-LNO CE show an excellent power conversion efficiency (η) of 5.84% with short-circuit current ($$ of 18.76 mAcm^-2, and open-circuit voltage ($$ of 0.80 V which is higher than Pt-based CE (η of 4.05% with $$ of 10.16 mAcm^-2, and $$ of 0.69 V). The DSSCs fabricated with 5-LNO CE exhibit excellent photovoltaic performance because of their high active surface area and enhanced electrical conductivity. The 5-LNO CE has low cost, significant electrocatalytic activity, less toxicity, and superior device efficiency than NiO, other Li (1-3%)-NiO, and Pt CEs, making it a suitable candidate for Pt-free DSSCs application.